The Greek coastguard and navy vessels are involved in an operation to rescue about 130 people from a yacht in trouble off the island of Crete, officials have said.
Coastguard authorities said in a statement that the vessel was taking on water about 30 nautical miles (34 miles) south-east of Koufonissi.
A passing cargo vessel had begun collecting the passengers of the stricken 115ft (35m) boat, the coastguard said.
There was no immediate information on the nationalities of the people on board.
Greece is the main point of entry for migrants trying to enter the European Union illegally. Tens of thousands cross the border from Turkey or sail to the country's southern islands from North Africa each year.