The Latest on the flow of refugees and other migrants into Europe (all times local):

11:55 a.m.

Greece's government has submitted draft legislation to parliament required for a landmark migration agreement reached this month by the European Union and Turkey to take full effect.

The bill, due to be voted on late Friday, would upgrade Greek asylum services and set conditions for refugees and migrants to be sent back to Turkey from the Greek islands.

The returns are due to start Monday, but most support staff promised by European Union countries have still not arrived on Greek islands, and the method of return is still being negotiated between the EU, Turkey and Greece.

More than 3,000 people who have arrived since March 20 have been arrested and are being detained on Greek islands. A detention facility on the island of Chios is already nearly 50 percent over capacity, with protests by detainees occurring daily.

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11:15 a.m.

Greek authorities say a fight broke out overnight between groups of migrants camping out in Greece's main port of Piraeus, injuring eight.

The coast guard said Thursday the three-hour fight, believed to have been between Afghans and Syrians, broke out at about 10 p.m. Wednesday. The aftermath was visible Thursday, with rocks and broken glass strewn on the street.

Eight people were being treated in a nearby hospital.

More than 50,000 refugees and migrants are stranded in Greece after Balkan countries closed their borders to the massive refugee flow. Under a European Union-Turkey agreement, those arriving from the nearby Turkish coast to Greek islands since March 20 will be sent back.

Hundreds of those camping out in Piraeus were boarding buses Thursday for refugee camps elsewhere in Greece.