Greece's coast guard says it has rescued 922 people over the past three days as they attempted to reach eastern Aegean islands clandestinely from the nearby Turkish coast.

The coast guard said the migrants and refugees were picked up in 32 search and rescue operations from Friday morning to Monday morning off the islands of Lesbos, Chios, Samos, Agathonissi, Kalymnos, Kalolimnos, Kos, Symi and Rhodes.

More than 250,000 asylum seekers have passed through Greece so far this year. The vast majority are Syrians, Iraqis and Afghans fleeing conflict at home. Most cross to Greek islands in overcrowded inflatable dinghies and other boats, and then head north overland through the Bakans, aiming for the more prosperous European Union countries such as Germany, Austria and the Scandinavian nation.