At least four people have been found dead on a cargo ship carrying around 900 migrants, which was found adrift in Greek waters, the Red Cross says.

The Blue Sky M had been abandoned and left on autopilot by its crew, believed to be people traffickers.

Italian coastguards later brought it under control and safely docked it at the Italian port of Gallipoli.

The migrants, believed to be mainly Syrians and Kurds, have been taken to a local school and gymnasium.

Thirty-five of them were taken to hospital, with some treated for hypothermia, Italian Red Cross spokeswoman Mimma Antonacci said.

Officials earlier put the number of migrants found at 700.

"We are talking not about 700 people on this boat but we are talking about around more than 900. They are now in all the schools around Gallipoli and they are recording now and trying to find out the names, but we're talking about Syrians," she added.

Ambulance crews stood waiting as the ship docked in the early hours of New Year's Eve.

A local eyewitness in Gallipoli, Gilberto Busti, told the BBC World Service he had seen hundreds of people - who he thought could be Syrian and Kurdish refugees - disembarking from the vessel.

Italy has had to deal with a massive surge in migrants - many of them from the Middle East and the Horn of Africa - setting off on boats with hopes of reaching Europe.

The most common sea route for the clandestine voyages has been from Libya but this ship is said to have started in Turkey. It is also unusual to find a vessel of this size carrying migrants.

People traffickers who organise the crossings often abandon the vessels at sea to avoid arrest.

'Disaster averted'

The Blue Sky is listed as a general cargo ship, flying under a Moldovan flag.

The safety manager of a company hired to provide safety certification for the ship told the BBC he had withdrawn its certificate several months ago after finding it unsafe.

Italian coast guard spokesman Filippo Marini was quoted by AP news agency as saying the Italians had averted a disaster by interrupting the programmed route that would have had the ship crash into the shore.

"It was a real race against the clock," he said, adding: "Unlocking the engines was a difficult and delicate operation, but they managed to do it."

Greek officials were first alerted to the ship when it was near Corfu.

A man aboard is reported to have asked for food, water and blankets. The distress call to Greek emergency services prompted the navy to send a helicopter and a warship.

The Greek authorities had said no-one aboard the vessel was in danger.

The Blue Sky M was reportedly heading for the port of Rijeka in Croatia from Turkey.

According to tracking website MarineTraffic, the ship abruptly changed direction south of Othonoi on Tuesday morning, heading west towards Italy.

Weather conditions in the Ionian sea have been poor for several days, hampering the rescue of those on board the Norman Atlantic ferry which caught fire in the area, killing at least 10 people.