Argentine navy submarine ARA San Juan docked in Buenos Aires in 2014. [ARGENTINE NAVY/AFP/File / Handout]

The wreckage of an Argentine navy submarine that exploded and disappeared one year ago was located in the Atlantic Ocean on Friday, said the navy, crushing the last hopes for relatives of the 44 crew.

There has been "positive identification of the ARA San Juan," at a depth of 800 meters (2,600 feet), a statement on Twitter from the navy said.

The Seabed Constructor, a vessel owned by US search firm Ocean Infinity, which set out in September on the latest attempt to find the San Juan, made the discovery.

The navy lost contact with the submarine on November 15 last year, about 450 kilometers (280 miles) from the Argentine coast. It was on its way back to base from Ushuaia at the southern tip of Argentina.

"I still had hopes that they could be alive," Luis Niz, the father of one of the missing sailors, told reporters, even though the government of President Mauricio Macri had earlier declared that there were no survivors from the San Juan.

"We are with the other relatives. They are going to show us the photos. They say that our youngsters are inside," said Yolanda Mendiola, the mother of crewman Leandro Cisneros, 28.

"We are all destroyed here."

The Ocean Infinity ship "decided to do a new search and, thanks to God, it was able to find the zone," navy spokesman Rodolfo Ramallo told Todo Noticias TV.

"Now another chapter opens. From the analysis of the state in which the submarine has been found, we will see how to proceed," he said.

The navy has been fiercely criticized for its handling of the operation since first reporting the submarine overdue at Mar del Plata on November 16, 2017.

It was only several days into the tragedy that navy officials acknowledged the old, German-built submarine had reported a problem with its batteries in its final communication of November 15.

Nearly 10 days later, the navy confirmed there had been an explosion on board, which experts said was likely linked to the battery problem.

Several senior officers were dismissed, including navy chief Marcelo Srur.

-- The 'last' chance --

Relatives and friends of crew members on the ARA San Juan mourn during a ceremony at Mar del Plata's naval base on November 15, 2018, a year after the vessel disappeared. [TELAM/AFP / Diego IZQUIERDO]

An air and sea search involved units from 13 countries but the majority withdrew before the end of 2017, as the wintry South Atlantic refused to give up its secrets.

The Seabed Constructor is equipped with cameras that can be submerged to a depth of 6,000 meters (yards). It was to receive a reward of $7.5 million if it found the missing sub.

Before it departed for its mission, Luis Tagliapietra, whose son Alejandro was a lieutenant on the San Juan, described it as "the last opportunity to find them."

Ocean Infinity was also assigned the task of searching for the Malaysia Airlines flight MH370 which vanished without trace in March 2014 en route from Kuala Lumpur to Beijing.

The navy has a poor reputation in Argentina.

During the 1976-1983 military dictatorship, some navy facilities, like the one at Mar del Plata, served as detention and torture centers, and an estimated 30,000 people disappeared.

Authorities have opened a criminal investigation into the San Juan's disappearance. The judge heading the case has so far heard testimony from 70 people but says she is no closer to knowing what happened.

Families of the missing crew had kept up pressure on the government not to give up on the search.

Several grieving mothers of the missing have turned up every morning in a forlorn protest at the sub's home base in Mar del Plata.

The submarine disappeared on the edge of the Argentine shelf where depths plummet from 200 meters (650 feet) to more than 3,000 meters.

Experts say the sub would have been crushed by water pressure once it dropped below about 600 meters.

The loss of the San Juan is the first major tragedy to hit the navy since the Falklands War in 1982. Argentina, which refers to the islands as Las Malvinas, lost the war to Britain.