The Greek coast guard says 11 people are missing after a ferry was engulfed in a blaze as it sailed between Greece and Italy after scores of other passengers and crew members were rescued.

The coastguard said, in total, 239 passengers and 51 crew members had been on board the Italian-flagged Euroferry Olympia and most of them had boarded rescue vessels transferring them to the port of the island of Corfu where ambulances were waiting.

The cause of the fire was still being investigated, Greek authorities said. There were no immediate reports of deaths or severe injuries.

One person with breathing problems had been taken to the hospital, according to local health authorities.

Two still trapped in ferry garage

Passengers huddled in yellow blankets on an Italian rescue vessel as huge plumes of smoke poured out of the ferry, one video showed.

The words "May Day" were repeatedly blasting from speakers on the ferry, in more footage uploaded on Greek news website Proto Thema.

Greek media reported that at least 10 were feared missing. Authorities could not confirm the information, saying the operation was ongoing.

A helicopter was waiting to airlift two passengers still trapped in the ship's garage, the coastguard said.

The 183-metre ferry had sailed from Igoumenitsa, the largest port in western Greece, and was headed to the Italian port of Brindisi, about nine hours away.

It carried 153 vehicles, many trucks among them, Grimaldi Lines, the owner of the vessel said.

Greek and Italian authorities on the scene

The fire broke out when the ship was near the island of Corfu in the Ionian Sea.

Hours after the alarm was raised, the vessel was still ablaze, drifting in Albanian waters, Grimaldi Lines said.

The ferry is part of the fleet of group Grimaldi Lines and has a capacity of up to 560 passengers, according to the company's website.

Grimaldi Lines spokesman Paul Kyprianou told Reuters that the cause of the fire was still under investigation but there were indications it started from the ship's hold.

The company was making every effort to help bring the passengers — most of them from Bulgaria, Romania and Turkey — home, he added.

At least four Greek coastguard vessels, four aircraft and the Italian financial police patrol boat Monte Sperone were involved in the rescue operation.

"The flames were incredibly high, we were a few miles away from the ferry when it happened," Colonello Felice Lodovico Simone Cicchetti from Italy's financial police, who took part in the operation, said.

Ship tracking data provided by Refinitiv Eikon showed the Euroferry Olympia performing a U-turn northwest of the North Corfu channel.

In 2014, 10 people were killed when the car ferry Norman Atlantic carrying 466 passengers and crew caught fire while sailing from Greece to Italy.

Reuters