The Minerve submarine was lost off France's southern coast with 52 sailors on board on January 17, 1968

A French submarine that went missing in the western Mediterranean in 1968 has been found, officials said Monday, ending a 51-year wait for families of the crew who continue to seek answers to the naval disaster.

The diesel-electric Minerve submarine was lost off France's southern coast with 52 sailors on board on January 27, 1968.

"We found the submarine Minerve last night located 45 kilometres (30 miles) south of Toulon, about 20 kilometres further south than where it was searched for in 1968," the French maritime prefect of the Mediterranean, Vice Admiral Charles Henri du Che, told reporters in Toulon.

Defence Minister Florence Parly on Twitter hailed the discovery as "a success, a relief and a technical feat", adding she was thinking of the families who had "waited for this moment for so long."

At the start of the year, Parly announced a new search mission involving naval vessels and marine experts following fresh demands from families for an effort to find the final resting place of their loved ones.

"It's a relief, hugely emotional," the son of the Minerve's captain, Herve Fauve, told AFP after years of calling for the search mission. "These 52 sailors had been abandoned in some ways."

Tides and currents in the western Mediterranean were modelled by the French team, as well as seismic data from the time that indicated the likely implosion of the vessel as it dropped to the seabed.

The discovery was ultimately made on Sunday by a boat belonging to private US company Ocean Infinity, which found the Minerve at a depth of 2,370 metres (7,800 feet), a senior French naval officer told AFP.

The search vessel -- the Seabed Constructor, which is equipped with underwater drones with powerful cameras -- arrived on the scene last Tuesday, the officer said on condition of anonymity.

The Seabed Constructor was also successful in locating Argentina's lost San Juan submarine in November 2018 which disappeared in the Atlantic Ocean a year earlier.

- Naval mystery -

The cause of the loss of the Minerve has never been confirmed but the news that it has been found fought joy and relief to families.

"I can't find the words to describe my emotion," the wife of one of the lost sailors, Therese Scheirmann-Descamps, told AFP on Monday from her home in Toulon where she lives surrounded by black-and-white pictures of her husband Jules.

"It's extraordinarily soothing, for my children too. It's such a surprise, such a joy," she added.

Fauve, who maintains a detailed website on the disaster, said there was unlikely to be any trace of the bodies.

Earlier this year, Jacques Dannay, who was just two when his father disappeared on board, said he was hoping the search mission would give him closure.

"I know it's stupid, but for me my father isn't really dead for as long as we haven't found the wreck," he told AFP as the new search mission began. "If someone told me he was alive, I'd probably believe them."

In keeping with naval tradition, du Che said the wreck would be left where it is and not touched.

"It is a maritime sanctuary, as is the case for all shipwrecks," he said.

- 'Deadly year' -

The Minerve was on a training mission in bad weather early on January 27 when it went down while returning to its base in Toulon, France's main Mediterranean naval port.

Experts have speculated that the disaster was caused by a problem with the Minerve's rudder, a collision with another boat, the explosion of a missile or torpedo, or a fault with its oxygen supply systems.

France is a world leader in submarine technology and its modern-day fleet of nuclear-powered vessels are seen as a key part of its defence capabilities and independence.

The year 1968 saw the loss of three other submarines around the world.

The USS Scorpion sank in the Atlantic, while the Soviet K-129 submarine armed with three nuclear missiles disappeared in the North Pacific.

It was found by the US in a covert operation in 1974.

The year was also marked by the disappearance of The Dakar, an Israeli vessel on its maiden voyage with 69 men on board. It was only found off the Greek island of Crete in 1999.