Officials said the “Alpha 1”, which is belongs to the Greek company Viamar, was carrying 1,800 tonnes of crude oil and 235 tonnes of diesel when it foundered.
Eleven crew members were on board when the boat started to sink. Ten people have been rescued while one of them has been hospitalized.
A rescued seaman said that the sea was calm and he did not understand why the emergency alarm went off.
“I realized that the boat was sinking but I was not able to understand why” the crew member said.
The captain of the vessel was on the bridge as the boat was sinking. Authorities said the captain was a 48 year-old Greek citizen and father of three.
The vessel may have sunk after hitting an old shipwreck, a coastguard said, adding that there were no signs of any oil spill or pollution so far. Rescue boats are still in the area.