BUENOS AIRES — Argentina’s Navy could not confirm Sunday if seven brief satellite calls received a day before were from a lost submarine with 44 crew members on board, as a multinational search for the sub continued.

‘‘We do not have clear evidence that [the calls] have come from that unit,’’ said Admiral Gabriel Gonzalez, chief of the Mar del Plata Naval Base. ‘‘We are analyzing more closely to reliably determine that they were not calls coming from the submarine.’’

American satellite communications experts are assisting Argentina in trying to locate the submarine.

Gonzalez said the Navy has intensified its aerial search off the country’s southern Atlantic coast after adverse weather conditions spurred waves up to 26 feet and made a maritime search difficult.

Navy spokesman Enrique Balbi said the low-frequency satellite signals received Saturday lasted a ‘‘few seconds,’’ but had not connected with a base, partly because of inclement weather. The communication attempts were originally thought to indicate that the crew was trying to reestablish contact.

On Sunday, search units were largely relying on information gathered from a British polar exploration vessel, the HMS Protector, which was equipped with an underwater search probe and was following the path taken by the submarine, the ARA San Juan.

The response of the British Royal Navy has attracted attention because the nations fought a bloody war in 1982.

Gonzalez also confirmed the US Navy’s Undersea Rescue Command had been deployed to the search area, along with aircraft from Argentina, Brazil, and the United States, and 11 surface vessels.

Among the ARA San Juan’s 44 crew members is Eliana Krawczyk, the first female submarine officer in Argentina.

Authorities said the submarine left the extreme southern port of Ushuaia on Wednesday and lost contact as it was heading to Mar del Plata, a city on the country’s northeastern coast.

The three-decade-old diesel-electric submarine suddenly stopped communicating during a routine mission.

The satellite signals came into different bases on Saturday between 10:52 a.m. and 3:42 p.m., according to CNN. The shortest was four seconds; the longest 36.

A US company that specializes in satellite communications has been added to the growing international search mission combing the waters of the Atlantic and listening to all frequencies for signs of the sub.

The Argentine navy has said the San Juan has multiple ways of communicating, as well as ample food and oxygen. Its protocol is to surface if there’s a communications blackout.

‘‘There must have been a serious problem with the communications [infrastructure] or with the electrical supply, cables, antennas, or other equipment,’’ Balbi told the Associated Press.

Worried relatives had gathered at the submarine’s base, where they hoped to hear updates.

‘‘We are praying to God and asking that all Argentines help us to pray that they keep navigating and that they can be found,’’ Claudio Rodriguez, the brother of one of the crew members, told the local Todo Noticias TV channel. ‘‘We have faith that it’s only a loss of communications.’’

Submarines are often among a country’s most expensive and complex military assets, and very vulnerable during accidents or times of crisis.

Over the years, several submarines have vanished, often igniting mysteries that lasted decades.

On May 27, 1968, the USS Scorpion failed to return to port, unexplainedly sinking 11,220 feet beneath the Atlantic Ocean along with its 99 crewmen and two nuclear torpedoes, according to USA Today.

A Navy inquiry found that the cause of the sinking ‘‘cannot be definitively ascertained’’ ­— and the cause of the sub’s demise remains fuzzy decades later.

Theories abound: a torpedo self-fired into the ship, destroying it from the inside, or a battery exploded, inflicting critical damage. The Navy has denied a proposal by civilian marine disaster experts to investigate the wreckage.

In August 2000, the Russian nuclear submarine Kursk suddenly sank during a planned and closely monitored Russian military exercise, killing all 188 sailors aboard, according to The New York Times. It was hours before the Russian government even knew something was amiss.

The most likely explanation was that fuel in a torpedo detonated, setting off a chain reaction in a sub once deemed unsinkable.

The Russians have said the Kursk used an outdated and unstable hydrogen peroxide propellant.