The Greek coast guard is searching for a boat believed to be carrying 45 migrants and to have run into trouble south of the small Ionian island of Antipaxoi, off the western coast of mainland Greece.

Two coast guard boats, a helicopter and one more boat sailing in the area were searching for the vessel Tuesday afternoon after one of those on board made a call requesting help, the coast guard said. It was not immediately clear what problem the boat was experiencing or where those on board were from.

Tens of thousands of migrants cross from the nearby Turkish coast into Greece each year, hoping to make their way to more prosperous European Union countries. Others try to go overland through Macedonia, or attempt to sail to Italy.