Hopes that the missing Argentinian submarine had been found have been dashed after a blurry sonar image of an object deep in the Atlantic turned out to be a sunken fishing vessel.

Rescuers had sent an unmanned Russian submersible to review the 197ft object located at 1,565 feet below sea level.

The ARA San Juan, that went missing on November 15 with 44 crew on board, was 216 feet in length – and officials said the image was “unclear.”

They sent the submersible to “visually verify” if it was indeed the San Juan.

“It was confirmed that it wasn’t the submarine’s shell” but a sunken fishing vessel, Argentine navy spokesman Enrique Balbi said on Saturday.

The navy “regrets that without a rigorous analysis expectations were generated in the families and society, which must now face another frustration,” Mr Balbi said.

Before Mr Balbi’s announcement, authorities had said that if the image did not reveal any new clues, the search would focus on other signals of interest detected in parts of the South Atlantic where the vessel was last heard from.

Argentina’s navy said on Thursday that it is no longer looking for survivors although a multinational operation will continue searching for the vessel. “The extreme environment, the time elapsed and the lack of any evidence eliminates a scenario compatible with human life,” Mr Balbi said.

“These are hours of intense pain and anguish (for relatives) in light of the loss of their loved ones, our 44 comrades,” he said.

The German-made submarine went missing as it was travelling from the extreme southern port of Ushuaia 2,500 miles to its base in the city of Mar del Plata.