At least seven fishermen have died and another 14 are missing after a Spanish trawler sank in rough seas off eastern Canada today, Spanish and Canadian officials said.

"We have now recovered seven deceased individuals and three survivors," Brian Owens of Canada's Joint Rescue Coordination Centre (JRCC) said.

There were 24 crew members on board the vessel when it went down some 250 nautical miles east of Newfoundland, with rescuers still searching for the remaining 14 crew despite difficult weather conditions, he said.

Spain's transport ministry identified the crew members as 16 Spanish nationals, five Peruvians and three Ghanaians.

"Seven people have been found dead... three sailors were found alive in a life raft, we believe they are recovering, and the rest - up to 24 - have not been found," Alberto Nunez Feijoo, head of Spain's northwestern Galicia region, told RTVE public television.

The Villa de Pitanxo, a 50-metre fishing vessel which is based at a port in Galicia, sent out two distress calls which were received at 5:24am in Madrid, the ministry said.

Only three survivors in one life raft

Five hours later, another Spanish fishing vessel that was in the area spotted two life rafts, one of which was carrying three survivors and several bodies, it said.

Rescuers later found another four bodies.

"In one, there were just three survivors who were in a state of hypothermic shock because the temperature of the water is horrible, very low," Maica Larriba, a representative of Spain's central government in the Galicia region, told public radio.

She said the survivors had been airlifted to safety by a Canadian coastguard helicopter and that rescuers had found two other life rafts that were "totally empty" while searching for a third.

Hopes that more survivors will be located

Canadian rescuers said they were hopeful more survivors could be found.

"The fact that we have already found three survivors in a life raft gives us that hope that others were able to either get into their survival suits, get into life rafts and get off the vessel," Mr Owens said.

Canadian rescuers had deployed a helicopter, a military plane, a coastguard ship and several boats to search for the missing crew members, he said.

"The weather right now is challenging for the search. It's approximately four-metre waves and visibility is down to approximately one quarter nautical mile," he said.

It was not immediately clear what caused the boat to founder.

"We certainly could be talking about one of the saddest days for Galician fishing in its entire history," Javier Touza, head of the Shipowner's Cooperative in the northwestern Spanish city of Vigo told public radio.

The Villa de Pitanxo is a freezer trawler registered in 2004 that is based in Marin, a small port near Pontevedra, and belongs to shipowner Manuel Nores.

Founded in 1950, the firm has eight freezer trawlers and some 300 employees with vessels operating off the Canadian coast, in the South Atlantic and off the western coast of Africa, according to its website.

"We are following with concern the search and rescue operation for the crew of the Galician ship that sunk in the waters of Newfoundland," Spanish Prime Minister Pedro Sanchez tweeted.

"All my love to their families. The government remains in constant contact with rescue services," he added.

Labour Minister Yolanda Diaz, who is from Galicia, said she was "shocked" by the news of the accident.

"Bad news is reaching us from the other side of the Atlantic," she tweeted.

"All my love and support to the families of the crew in their pain at this time of uncertainty."