Three people drowned and more than a dozen were believed to be missing in the second migrant shipwreck off Greece this week, authorities said on Tuesday.

The coast guard said 19 people were rescued in an operation that began in the early hours of Tuesday after an inflatable rubber boat was spotted on rocks along the coast of the island of Lesbos, near Turkey.

At least 10 people were taken to hospital, authorities said, some suffering from hypothermia as a cold weather front brought freezing temperatures and snow across many parts of Greece this week.

Survivors told authorities about 41 people were on board the dinghy that had sailed from the Turkish coast. Two coast guard vessels and a Super Puma helicopter were assisting in the search operation amid strong winds, the coast guard said.

State broadcaster ERT said the migrants were from Syria, Yemen and Somalia, citing survivors' accounts.

Greece has long been one of the main entry points into the European Union for refugees and migrants from the Middle East, Africa and Asia. Most cross on inflatable boats from Turkey, a short but perilous journey during which thousands have died.

Four migrants, including three children, died after their boat sank off the island of Leros in the southeastern Aegean Sea on Sunday. (Reporting by Karolina Tagaris, Editing by Kylie MacLellan and Andrew Cawthorne)