Argentina's defense ministry has detected 'satellite calls' it believes came from the missing submarine. The ARA San Juan disappeared three days ago while on a routine mission.
The Argentine defense ministry said on Saturday that seven, failed "satellite calls" lasting between four and 36 seconds late morning and early afternoon could be signs the crew of the ARA San Juan were trying to reestablish contact.
In an emailed statement, the ministry said it was working to trace the location with a US company specializing in satellite communications.
The Argentine Navy announced on Saturday that it was ramping up the hunt for a submarine that disappeared three days previously, despite the rough weather hampering the search. At least six other nations have offered to aid in the mission to recover the vessel and the 44 crew members aboard.
"The weather is bad. There is a storm with waves of six meters (nearly 20 feet)," navy spokesman Enrique Balbi said at a press conference. "It really complicates the work."
The ARA San Juan, a TR-1700 class diesel electric submarine, was heard from Wednesday morning before contact was lost. The vessel was returning from a routine mission to the southern tip of South America on its way back to its base at Mar del Plata, some 400 kilometers (240 miles) south of Buenos Aires. The last point of communication was off the coast of Chubut in the country's south.
Balbi initially theorized that the vessel had suffered an electrical outage, which would account for its lack of communication.
One of the crew on board was 35-year-old Eliana Krawczyk, Argentina's first female submarine officer.
Massive international search
Argentina immediately launched a sea and air hunt for the submarine. A search of 80 percent of the target area turned up no sign of the vessel, but the crew should have ample supplies of food and oxygen, Balbi added.
President Mauricio Macri wrote on Twitter that he would call upon "all resources national and international that are necessary to find the submarine."
Pope Francis, an Argentine, was praying "fervently" for the crew to return home soon, his office said.
The governments of Chile, Uruguay, Brazil and Peru have all pledged their help, while the United States has sent a NASA scientific aircraft to help in the search. Britain sent its polar expedition vessel the HMS Protector, which was set to arrive early Sunday.
One of the three submarines in Argentina's fleet, the ARA San Juan was built in Germany in 1983. It was re-built between 2007 and is expected to continue to be in service for a another 30 years.
es/jm (AFP, AP, Reuters, LUSA)