Thousands of sheep were feared dead Monday a day after a vessel overturned off the Romanian coast, leading to renewed calls for a ban on the controversial sea transport of livestock.

The Queen Hind, bound for Saudi Arabia with 14,600 sheep aboard, capsized on Sunday shortly after leaving Midia port on the Black Sea in eastern Romania -- no explanation has been given.

The crew of 20 Syrians and one Lebanese were rescued along with 32 sheep.

The rescued sheep have been taken to a special shelter in Midia.

No one has been able to board the vessel to check its hold but photos and video footage distributed by rights group Animals International showed dead sheep in the ship and dozens floating in the sea nearby.

Rescuers were trying tow the Palau-flagged vessel back to the dock, less than a kilometre (mile) away, battling stormy weather and rough seas.

Ana-Maria Stoica of the local rescue services told AFP workers were trying to remove the cargo refloat the ship.

She said once this was done, rescuers would be able to take out the remaining sheep. "We hope that some of them are still alive," she added.

Mihaita Gheba, chief of the local veterinary authority, said the dead sheep would be burned while surviving ones would be returned to the breeder.

So far only 32 sheep have been rescued after the Queen Hind capsized on Sunday off the Romanian coast
So far only 32 sheep have been rescued after the Queen Hind capsized on Sunday off the Romanian coast IGSU Romania / -

Romania joined the EU in 2007 and is the bloc's third-largest sheep breeder and a top exporter, primarily to Middle Eastern markets.

Romania's main livestock breeders and exporters' association Acebop has called for an urgent investigation, saying it was "shocked by the disaster".

"If we cannot protect livestock during long-distance journeys, we should outright ban them," Acebop president Mary Pana said in a statement late on Sunday.

Acebop has previously called for legal changes that would oblige transporters to improve conditions aboard livestock carriers.

Gabriel Paun of Animals International has also called for an inquiry to be held "without delay", alleging that the ship had been overloaded.

He added that the Queen Hind already had engine problems last December.

The veterinary authority said in a statement that the vessel had fully complied with EU regulations and that sufficient space, food and water had been provided.

Activists have labelled the livestock transport vessels -- about 100 of which leave Midia every year -- "death ships", saying sheep risk being cooked alive on board during the hot summer months.

In July, the European commissioner in charge of health and food safety demanded that Bucharest stop the transport of 70,000 sheep to the Gulf, citing animal welfare.