Argentina’s Navy insists missing sub was in good condition

Hopes for survivors on the missing Argentinian submarine have dimmed further as the ARA San Juan entered its 10th day missing

Hundreds gathered outside an Argentinian naval base to support family of missing submariners. (AAP)

Argentina's navy insists that a missing submarine had seemed to be in good condition when it set off on a training mission, despite fears it later exploded beneath the sea with 44 crew members aboard.

Hopes for survivors, already largely crushed by reports of an explosion, dimmed further as the ARA San Juan entered its 10th day missing - which is what experts had said would likely be the limit of its oxygen supply even if it remained intact beneath the sea.

But a multinational search and rescue effort continued on Saturday, as a Norwegian ship carrying a US undersea rescue module prepared to weigh anchor for the search zone, despite worsening weather.

The German-built diesel-electric submarine set off on November 8 from the southernmost port of Ushuaia en route to Mar del Plata.

"Two days before setting sail, there was a check of the whole operating system," navy spokesman Enrique Balbi said as a news conference on Saturday.

"The submarine doesn't sail if that's not done. If it set off from Ushuaia, it was because it was in condition to do so."

Balbi said the captain reported on November 15 that there had been an electrical problem in a battery compartment. But he later communicated by satellite phone that the problem had been solved and that he would continue the voyage submerged toward Mar del Plata.

Since then, there has been no contact with the San Juan, and no signs of the ship or debris despite an intensive search.

But it was also on November 15 that both the US Navy and the international nuclear test ban monitoring agency detected what appeared to be an undersea explosion in the area where the sub was operating.

A relative of missing Argentine submarine crew member Alejandro Damian Tagliapietra, expresses her grief outside Argentina's Navy base. Source: Getty

Relatives of crew members have suggested that the 33-year-old vessel, which was refitted in 2014, was in poor condition.

Hundreds of people from Mar del Plata gathered outside the naval base on Saturday to express solidarity with relatives of the crew, applauding them and shouting, "Be strong, we are with you".