At least four migrants have drowned after a boat thought to be carrying hundreds of refugees has capsized in the Mediterranean Sea.
Around 340 people have been rescued so far, with four bodies recovered, but many remained missing as operations continued south of the Greek island of Crete.
“The number of people in distress could be counted in the hundreds,” a spokeswoman for the coastguard told the AFP news agency.
“People are in the water, boats crossing the area have thrown lifebuoys and are moving to save the migrants.”
The coast guard said the 80ft vessel, believed to be a fishing boat, was found sinking by a passing ship around 75 nautical miles south of land on Friday.
Greece sent two patrol boats, a military plane and three helicopters to the area, while five ships that had been sailing nearby were participating in the rescue operation.
It was not immediately clear where the smuggling vessel had launched from, with Turkey, Egypt and Libya among the most likely possibilities. It was believed to be heading for mainland Greece or Italy.
A boat previously intercepted off the coast of Crete on 27 May was carrying 65 refugees from Syria, Afghanistan and Pakistan, controlled by people smugglers from Ukraine and Egypt.
Hundreds of asylum seekers have drowned in successive disasters in the Mediterranean Sea in recent weeks amid concerns that the EU-Turkey deal seeing migrants detained on Greek islands would force desperate migrants to take longer and more treacherous journeys.
The deal and Nato patrols have resulted in a dramatic decrease in the number of people crossing the Aegean Sea, where four boats carrying 164 people were intercepted off the islands of Lesbos and Chios on Thursday.
The vast majority of arrivals are now landing in Italy after crossing the Central Mediterranean from North Africa.
At least 880 migrants died last week alone and deaths are up more than a third compared to the same period last year, according to figures compiled by the United Nations refugee agency (UNHCR)
More than 2,500 migrants have died at sea in attempts to reach Europe this year, while more than 205,000 people have made the journey.
