ATHENS, Greece - 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 Defence 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.

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

Meanwhile, the humanitarian ship Ocean Viking rescued another 30 people from a boat in distress off the Libyan coast, bringing the total number of migrants aboard the rescue vessel to 125, Doctors Without Borders said on Twitter. Survivors said they had been at sea since late Tuesday night. The Ocean Viking brought hundreds of migrants to Italian ports last month.

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.

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.