Seven children drown as boats sink off Greek coast

At least seven children died when boats carrying refugees sank off Greece on Wednesday, as rescue workers battled to save more youngsters on the seashore in the latest desperate scenes in Europe's refugee crisis.

Three adults also died as four vessels went down on the dangerous sea crossing from Turkey and more than 200 people, many suffering hypothermia, were rescued from one sinking off the north coast of the Greek island of Lesbos.

Images from Lesbos, a major entry point for the huge flow of refugees trying to get to Europe, showed doctors attempting to revive unconscious children on the island's shoreline.

Later in the evening, a drowned woman and the bodies of two children were found floating off the Greek island of Agathonisi, just a few kilometres from the Turkish coast.

A one-year-old baby remained in a critical condition Wednesday night, according to port police.

Patrol vessels, fishing boats and even locals on jet skis joined in efforts to search into the night for more survivors in the water, struggling with strong winds.

Port police said it was not clear how many people might be in the water, with survivors giving a confusing picture of the number of people who were on the boat that capsized off Lesbos.

The new accidents brought to 39 the number of refugees found dead in Greek waters this month, according to an AFP tally based on data from Greek port police.