BUENOS AIRES, Argentina -- Argentina's Navy said Friday it has lost contact with a submarine carrying 44 crew members off the country's southern coast and has mounted an extensive search.

The Navy said that ships and aircraft were searching near the last known location of the ARA San Juan, a German-built diesel-electric vessel, which had not been heard from since Wednesday.

The Navy said it was scanning all possible radio transmission frequencies for a sign of the San Juan.

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Navy spokesman Enrique Balbi told The Associated Press that it is possible that the submarine had an electrical issue and said it could not yet be termed lost.

"The last position (registered) was two days ago. Without wanting to be alarmist or overdramatic, the facts are that there no form of communications could be established between the vessel and its command, even with the alternative methods that the submarine has," Balbi said.

"What we interpret is that there must have been a serious problem with the communications (infrastructure) or with the electrical supply, cables, antennae or other (onboard) equipment."

Adm. Gabriel Gonzalez, chief of the Mar del Plata base that was the submarine's destination, said the vessel had sufficient food supply and oxygen.

"We have a loss of communications; we are not talking of an emergency," he said.

Still, relatives of some of the crewmembers were at the base awaiting word of the search.

"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 crewmembers, told the local Todo Noticias TV channel.

"We have faith that it's only a loss of communications," he added.

Balbi said the sub was headed from the naval base at Ushuaia in Argentina's extreme south to Mar del Plata, about 250 miles southeast of Buenos Aires. He asked for patience while the search is carried out and said that the sub must surface so visual or radar contact can be made.

The Argentine Foreign Ministry said in a statement that the governments of Britain, Chile and the United States had offered "logistical help and an exchange of information for this humanitarian search." The statement also said that Argentina is also working with authorities in neighboring countries in case it needs support to locate the submarine.

The San Juan was commissioned in 1985 and was most recently refit in 2014.