Malaysia's former Prime Minister Mahathir Mohamad has been ousted from his ethnic Malay political party in the latest twist of a power struggle with his successor, but he has vowed to challenge the move.

The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday.

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FILE- In this Dec. 29, 2018, file photo, Malaysian Prime Minster Mahathir Mohamad, center, stands next to his son Malaysian United Indigenous Party Vice President Mukhriz Mahathir, right, and President Muhyiddin Yassin, left, during the Malaysian United Indigenous Party general assembly at Putrajaya International Convention Centre in Putrajaya, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoYam G-Jun, File)

Malaysia's former Prime Minister Mahathir Mohamad has been ousted from his ethnic Malay political party in the latest twist of a power struggle with his successor, but he has vowed to challenge the move.

FILE - In this July 17, 2018, file photo, Malaysian Prime Minister Mahathir Mohamad salutes during the opening of the 14th parliament session at the Parliament house in Kuala Lumpur, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoYam G-Jun, File)

Mahathir’s son Mukhriz Mahathir had since challenged Muhyiddin as party president in a vote that's been postponed by the coronavirus pandemic.

FILE - In this Feb. 27, 2020, file photo, Malaysian interim leader Mahathir Mohamad speaks during a press conference at his office in Putrajaya, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoVincent Thian, File)

The ruling alliance collapsed after Muhyiddin pulled Bersatu out to work with the former government, which has been accused of massive corruption. Mahathir, a two-time prime minister, resigned in protest.

In this May 9, 2018, photo, Mahathir Mohamad, right, speaks to media during a press conference to announce victory on election as Muhyiddin Yassin, president of Malaysian United Indigenous Party stands next to him at a hotel in Kuala Lumpur, Malaysia. Malaysian ex-Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge it. (AP PhotoVincent Thian)

Party letters sent to the five said their membership had ceased as they sat with the opposition bloc during a half-day Parliament sitting on May 18. But the letter was signed by a lower official who Mahathir’s group and others said had no power to remove them.

FILE - In this March 27, 2016, file photo, Malaysia's former Prime Minister Mahathir Mohamad, right, and former Deputy Prime Minster Muhyiddin Yassin attend the "People's Congress 2016" event in Shah Alam, Malaysia. Malaysian ex-Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge it. (AP PhotoVincent Thian, File)

The current government includes the party of ex-Prime Minister Najib Razak, who is on trial on charges related to a massive financial scandal.

The party has has been split into two camps since intense political wrangling led Mahathir to resign the premiership in February and the king to appoint fellow party member Muhyiddin Yassin as his replacement despite Mahathir's objections.

FILE- In this Dec. 29, 2018, file photo, Malaysian Prime Minster Mahathir Mohamad, center, stands next to his son Malaysian United Indigenous Party Vice President Mukhriz Mahathir, right, and President Muhyiddin Yassin, left, during the Malaysian United Indigenous Party general assembly at Putrajaya International Convention Centre in Putrajaya, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoYam G-Jun, File)

FILE- In this Dec. 29, 2018, file photo, Malaysian Prime Minster Mahathir Mohamad, center, stands next to his son Malaysian United Indigenous Party Vice President Mukhriz Mahathir, right, and President Muhyiddin Yassin, left, during the Malaysian United Indigenous Party general assembly at Putrajaya International Convention Centre in Putrajaya, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoYam G-Jun, File)

Mahathir’s son Mukhriz Mahathir had since challenged Muhyiddin as party president in a vote that's been postponed by the coronavirus pandemic.

“The unilateral action by Bersatu’s president to sack us without valid reason is due to his own fears in facing party elections as well as his unsafe position as the most unstable prime minister in the history of the country’s administration,” a joint statement by Mahathir and the four others read.

Mahathir co-founded Bersatu with Muhyiddin in 2016, and the party joined an alliance that won a stunning victory in 2018 polls, leading to the first change of government since independence.

FILE - In this July 17, 2018, file photo, Malaysian Prime Minister Mahathir Mohamad salutes during the opening of the 14th parliament session at the Parliament house in Kuala Lumpur, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoYam G-Jun, File)

FILE - In this July 17, 2018, file photo, Malaysian Prime Minister Mahathir Mohamad salutes during the opening of the 14th parliament session at the Parliament house in Kuala Lumpur, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoYam G-Jun, File)

The ruling alliance collapsed after Muhyiddin pulled Bersatu out to work with the former government, which has been accused of massive corruption. Mahathir, a two-time prime minister, resigned in protest.

Mahathir has said he still has the majority support of lawmakers and has called for a no-confidence vote against Muhyiddin. The vote has been delayed amid the pandemic but could be held at the next sitting of Parliament in July.

In their statement, Mahathir and the other expelled members said the move was illegal and they may take legal action to challenge their termination and ensure Bersatu isn't used as a vehicle for those crazy for power.

FILE - In this Feb. 27, 2020, file photo, Malaysian interim leader Mahathir Mohamad speaks during a press conference at his office in Putrajaya, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoVincent Thian, File)

FILE - In this Feb. 27, 2020, file photo, Malaysian interim leader Mahathir Mohamad speaks during a press conference at his office in Putrajaya, Malaysia. Former Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge the move. The 94-year-old Mahathir, along with his son and three other senior members, were expelled from the Bersatu party on Thursday, May 28, 2020. (AP PhotoVincent Thian, File)

Party letters sent to the five said their membership had ceased as they sat with the opposition bloc during a half-day Parliament sitting on May 18. But the letter was signed by a lower official who Mahathir’s group and others said had no power to remove them.

“All eyes are on Mahathir’s next move," said Oh Ei Sun, a senior fellow at the Singapore Institute of International Affairs. “Muyhiddin would be gravely mistaken if he thinks this will slow down Mahathir’s relentless onslaught to not so much unseat him, but topple the present ruling coalition."

Muhyiddin had earlier tried to reconcile with Mahathir, but failed.

In this May 9, 2018, photo, Mahathir Mohamad, right, speaks to media during a press conference to announce victory on election as Muhyiddin Yassin, president of Malaysian United Indigenous Party stands next to him at a hotel in Kuala Lumpur, Malaysia. Malaysian ex-Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge it. (AP PhotoVincent Thian)

In this May 9, 2018, photo, Mahathir Mohamad, right, speaks to media during a press conference to announce victory on election as Muhyiddin Yassin, president of Malaysian United Indigenous Party stands next to him at a hotel in Kuala Lumpur, Malaysia. Malaysian ex-Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge it. (AP PhotoVincent Thian)

The current government includes the party of ex-Prime Minister Najib Razak, who is on trial on charges related to a massive financial scandal.

FILE - In this March 27, 2016, file photo, Malaysia's former Prime Minister Mahathir Mohamad, right, and former Deputy Prime Minster Muhyiddin Yassin attend the "People's Congress 2016" event in Shah Alam, Malaysia. Malaysian ex-Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge it. (AP PhotoVincent Thian, File)

FILE - In this March 27, 2016, file photo, Malaysia's former Prime Minister Mahathir Mohamad, right, and former Deputy Prime Minster Muhyiddin Yassin attend the "People's Congress 2016" event in Shah Alam, Malaysia. Malaysian ex-Prime Minister Mahathir has been ousted from his Malay party in the latest twist to a power struggle with his successor Muhyiddin Yassin, but he has vowed to challenge it. (AP PhotoVincent Thian, File)