ATHENS (AP) — Greece’s government is considering emergency measures to house migrants and refugees confined to Greek islands over the winter months following a roughly four-fold increase in the number of daily arrivals from Turkey.

Migration Minister Yannis Mouzalas said Wednesday that average arrivals had jumped since mid-August from about 50 per day to more than 200. He added the government could use ferries or military ships to provide additional housing space over the winter if alternatives provided by local municipalities were exhausted.

Under a 2016 deal between Turkey and the European Union, migrants and refugees reaching Greek islands from the Turkish mainland are not allow to travel to the Greek mainland before their asylum claims are examined.

Mouzalas said the agreement was not under threat but that the rise in migrant arrivals was “concerning.”

In central Athens, several dozen migrants protested Wednesday against delays in being relocated to other EU countries. They set up tents near the Greek parliament, and several protesters said they plan to launch a hunger strike.