ATHENS — Greece's coast guard on Friday launched a search and rescue operation after a boat carrying around 150 people believed to be migrants ran into trouble off the country's southwestern coast.

The coast guard said a passing cargo ship raised the alarm after coming across the wooden boat, which was taking on water, about 70 nautical miles (130 kilometers, 80 miles) southwest of the islet of Schiza off the coast of the Peloponnese.

The wooden boat's passengers were picked up by the cargo ship, a Marshall Islands-flagged tanker named Aristofanis.

A coast guard patrol boat, one air force helicopter and one navy helicopter were scrambled to the area and continued the search and rescue operation after one of the cargo ship's crew members told authorities he saw a woman fall into the sea as the boat's passengers were being transferred onto the larger vessel.

The Aristofanis was heading to the southern island of Crete, where the migrants were to disembark. The coast guard said there was no immediate information on their nationalities, or where they had set sail from or were heading to.

Greece is one of the most popular points of entry into the European Union for people fleeing conflict and poverty in the Middle East, Africa and Asia. But with Greek authorities cracking down on arrivals on eastern islands from the nearby Turkish coast, smugglers have appeared to be increasingly using larger vessels to ferry people past Greece and directly to Italy.