MAR DEL PLATA, Argentina (AFP) - Argentina's navy confirmed on Thursday (Nov 24) that an unusual noise heard in the Atlantic near the last known position of a missing submarine appeared to be an explosion, dashing the last hopes of finding the vessel's 44 crew members alive.

Relatives of the missing sailors reacted with grief and anger to the news after holding out hope since the sub was reported overdue at its Mar del Plata base on Nov 17, two days after the explosion.

"An anomalous, singular, short, violent and non-nuclear event consistent with an explosion," occurred shortly after the submarine's last communication, navy spokesman Captain Enrique Balbi told a news conference in Buenos Aires.

After days of false hopes, some of the relatives said the navy had withheld information about the sub and lied to them over the past week.

"I feel cheated," said Itati Leguizamon, whose husband German Suarez was a sonar operator on the ARA San Juan.

"They did not tell us they died. But they tell us they are three thousand meters deep," added Leguizamon as other family members shouted angrily around her.

"They lied to us," said Leguizamon, a lawyer.

A sobbing Jessica Gopar, whose husband was an electrician aboard the San Juan, said "they just told us that the submarine exploded." She spoke as she came out from the sub's base.

In the parking lot of the base, some of the relatives hugged, others slumped to the ground and cried inconsolably. Uniformed sailors at the base wept.

One woman, a relative of a crew member, approached a group of journalists but broke down in tears before she could say a word.

RELATIVES' VIGIL

Around 100 family members had been waiting hopefully inside the Mar del Plata naval base, the perimeter fence of which is festooned with messages of encouragement for the crew, religious images and Argentinian flags and banners.

Families of the crew, some from distant parts of Argentina, have been keeping vigil here since a multinational air and sea search began last Thursday.

Leguizamon described how navy officers broke the news of the explosion to the families.

"They asked most of the people to leave and just close family members to stay," she said.

"When they heard the news they all exploded in there, they jumped on them and they had to stop reading their statement. People became very aggressive."

"They are going to continue looking for it, because they have an obligation to do so," she said.

"They launched a search because it looks good. Because they sent shit out there to sail.

"They already had problems in 2014, because it couldn't surface. Now I don't care if everything is known, he's not here any more," she said, referring to her husband.

The German-built submarine was launched in 1983 and underwent a refit to extend its life from 2007 to 2014.

Suarez, she said, "was prepared for death". "He always went to confession and was at peace. He was ready."

'THEY'RE ALL DEAD'

"I've just learnt that I'm a widow," said Gopar, wife of Fernando Santilli, an electrician aboard the submarine, before bursting into tears.

After hearing the news of an explosion on board, her first reaction was: "They're all dead. It's the first thing I thought."

"We are going to get together and ensure we are going to get justice. I don't need a plaque that says 'the heroes of the San Juan'," she said before collapsing in tears.

"He was my great love, we were going out for seven years, married for six, 13 years together and now we have a son, Stefano.

"How do I tell my son that he is left without a father," said Gopar, who on Wednesday posted an emotional Facebook message to her husband, saying that her one-year-old had just learnt to say "dad".

Julian Colihuinca, 19, was at the perimeter fence, pinning up a plastic banner on which he had scrawled: "Be strong, the families of the 44."

"I'm the son of a tactical diver. The tragedy hits close.

"I know all the crew by their faces."

Outside the base, Hugo Daniel, 43, stopped as he was passing by on his bicycle.

Like the rest of the nation, he had been following the unfolding tragedy over the past week.

"It's a tragedy that will go down in history," he said. "Machines fail. The people who were on the submarine knew the risks."

Referring to the strained relationship between many Argentinians and their military, he said that during the 1976-83 dictatorship "they used to torture people here", pointing to a plaque on the fence that notes it was once a "clandestine detention centre".