Argentina's navy says searchers deep in the Atlantic have found the missing submarine ARA San Juan, which disappeared with 44 crewmen aboard almost a year ago to the date.

Key points: The navy said a "positive identification" had been made by a search ship

The navy said a "positive identification" had been made by a search ship The discovery was made two days after the one year anniversary of the disappearance

The discovery was made two days after the one year anniversary of the disappearance Argentina gave up hope of finding survivors after an intense search last year

The vessel was discovered more than 900 metres below the ocean surface in a canyon on the ocean floor with its tail partially "imploded", Argentina's Defence Minister Carlos Aguad said.

The navy said a "positive identification" had been made by a remote-operated submersible from the American ship Ocean Infinity, which was hired for the latest search for the missing vessel.

It had earlier tweeted that it was investigating a "point of interest" where a 60-metre-long object had been detected.

Loading

"We have found them," Jorge Villarreal, father of one crew member told local radio.

"Now we are going to search for the truth. For us this is the start of a new chapter."

The discovery was announced just two days after families of the missing sailors held a commemoration one year after the sub disappeared on November 15, 2017.

On Thursday, on the anniversary of the disappearance, President Mauricio Macri said the families of the submariners should not feel alone and delivered an "absolute and non-negotiable commitment" to find "the truth".

Mr Macri promised a full investigation after the submarine was lost. Federal police raided naval bases and other buildings last January as part of the probe, soon after the Government dismissed the head of the navy.

The discovery was announced just two days after families of the missing held a commemoration service. ( AP: Vicente Robles )

The San Juan was returning to its base in the coastal city of Mar del Plata when contact was lost.

The navy has previously said the captain reported on November 15 that water entered the snorkel and caused one of the sub's batteries to short-circuit. The captain later communicated that it had been contained.

Some hours later, an explosion was detected near the time and place where the San Juan was last heard from.

The navy said the blast could have been caused by a "concentration of hydrogen" triggered by the battery problem reported by the captain.

Argentina gave up hope of finding survivors after an intense search aided by 18 countries, but the navy has continued searching for the vessel.

The German-built diesel-electric TR-1700 class submarine was commissioned in the mid-1980s and was most recently refitted between 2008 and 2014.

During the $US12 million ($16 million) retrofitting, the vessel was cut in half and had its engines and batteries replaced.

Experts said refits could be difficult because they involve integrating systems produced by different manufacturers, and even the tiniest mistake during the cutting phase can put the safety of the ship and crew at risk.

Map of Argentina's San Jorge Gulf, the submarine's last known location.

AP