Greece announced plans Wednesday to overhaul its migration management system, replacing overcrowded refugee camps on the islands with smaller detention facilities and moving some 20,000 asylum seekers to the mainland over the next few weeks.

Deputy Defense Minister Alkiviadis Stefanis announced the changes following a surge in the number of arrivals from nearby Turkey —with the number of migrants and refugees now exceeding the islands’ populations in some cases.

Camps on Lesbos and four other islands in the eastern Aegean Sea are suffering dramatic overcrowding ahead of the winter, with hundreds of families sleeping in tents and often in poor sanitary conditions outside the official facilities.

On this Tuesday, Oct. 1, 2019 photo, an Afghan child stands next her family's belongings after disembarking from a ferry with other refugees and migrants at the port of Piraeus, near Athens. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)

On this Tuesday, Oct. 1, 2019 photo, an Afghan child stands next her family's belongings after disembarking from a ferry with other refugees and migrants at the port of Piraeus, near Athens. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)

“In the short term, we will return security and control to the areas affected by the crisis,” Stefanis said.

“Normal life will return to these areas and measures will be taken to safeguard them from future threats, with an emphasis placed on deterrence.”

The planned changes are the most significant since a landmark deal in 2016 between Turkey and the European Union to limit migration to Europe.

In this Saturday Oct. 5, 2019 photo, Afghan men prepare their tent after a rainfall, in a makeshift refugee and migrant camp on the fringes of the overcrowded Moria camp on the Greek island of Lesbos. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)

In this Saturday Oct. 5, 2019 photo, Afghan men prepare their tent after a rainfall, in a makeshift refugee and migrant camp on the fringes of the overcrowded Moria camp on the Greek island of Lesbos. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)

Greece’s four-month-old conservative government has vowed to step up deportations of migrants not eligible for asylum and build up a network of detention facilities to separate refugees from migrants and speed up the processing of asylum applications.

Rights groups, including Amnesty International and Human Rights Watch, have criticized the government plans, warning that migrants fleeing war zones may lose access to proper asylum screening.

Still, many of the changes announced Wednesday follow recommendations from European Union agencies which are urging a restart of deportations back to Turkey.

In this Wednesday, Sept. 25, 2019 photo, people wait outside the information office at a refugee and migrant camp of the Greek island of Samos. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)

In this Wednesday, Sept. 25, 2019 photo, people wait outside the information office at a refugee and migrant camp of the Greek island of Samos. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)

Mainland transfers, Stefanis said, will make use of off-season hotel vacancies as well as new camps around the country.

The program will be mostly funded by the EU, which has already paid Greece more than 2 billion euros ($2.2 billion) since the 2016 deal and has pledged to provide more support for funding, screening, and border protection.

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In this Friday Oct. 4, 2019 photo, a woman enters a tent in a makeshift refugee and migrant camp on the fringes of the overcrowded Moria camp on the Greek island of Lesbos. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)

In this Friday Oct. 4, 2019 photo, a woman enters a tent in a makeshift refugee and migrant camp on the fringes of the overcrowded Moria camp on the Greek island of Lesbos. Greece's conservative government announced Wednesday Nov. 20, 2019, plans to overhaul the country's migration management system, and replacing existing camps on the islands with detention facilities and moving and 20,000 asylum seekers to the mainland over the next few weeks. (AP PhotoPetros Giannakouris)