Local authorities declared a 24-hour strike on two eastern Greek islands Wednesday to protest government plans to build new migrant detention camps there.

The strike shut down services on the islands of Lesbos and Chios, which have been the main points of arrival for tens of thousands of people fleeing war or poverty in the Middle East, Asia and Africa.

The strike comes after protesters clashed with riot police on the two islands during efforts to prevent the arrival of excavating machines from the mainland to start construction of the new detention centers.

Protesters use an aim laser pointer to riot police during a rally in Karava near the area where the government plans to build a new migrant detention center, on the northeastern Aegean island of Lesbos, Greece, Tuesday, Feb. 25, 2020. Riot police and residents clashed for several hours on the Greek islands of Lesbos and Chios Tuesday, as protesters tried to prevent authorities from bringing excavating machines from the mainland to build new migrant detention camps. (AP PhotoMichael Varaklas)

Protesters use an aim laser pointer to riot police during a rally in Karava near the area where the government plans to build a new migrant detention center, on the northeastern Aegean island of Lesbos, Greece, Tuesday, Feb. 25, 2020. Riot police and residents clashed for several hours on the Greek islands of Lesbos and Chios Tuesday, as protesters tried to prevent authorities from bringing excavating machines from the mainland to build new migrant detention camps. (AP PhotoMichael Varaklas)

Greece is the main entry point for asylum seekers attempting to enter the European Union, with most arriving on the eastern Greek islands from the nearby Turkish coast. Under a 2016 deal between the European Union and Turkey, new arrivals must remain on those islands until their asylum claims are processed. But a massive backlog in the asylum system coupled with continued arrivals have led to severe overcrowding in existing facilities, which are several times over capacity.

Nearly 60,000 migrants and refugees arrived on Greek islands last year, almost double the number recorded in 2018, according to the U.N. refugee agency.

The government has vowed to move ahead with plans to build the new facilities and has promised to replace the existing overcrowded camps. But many island residents and local authorities argue the asylum seekers and migrants should be moved to the Greek mainland.