The Argentine Navy continues to coordinate with international allies in the search for its submarine, a media report said.
The submarine disappeared last Wednesday along the country’s Atlantic coast with 44 crewmen on board.
Helping to search for the ARA San Juan are Chile, Brazil, the US, the United Kingdom, Colombia, Uruguay and Peru, although other countries have offered their cooperation in the search and rescue operation, Argentine Defence Minister Oscar Aguad confirmed on Saturday, Efe news reported.
The last time the submarine reported was on Wednesday morning and when it continually missed the deadline for establishing communications again the search was launched on Thursday morning and is still underway.
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The US Southern Command on Sunday sent a second aircraft to assist in the operation, a P-8A Poseidon with a crew of 21 from Jacksonville, Florida, which is expected to arrive in Argentina in the coming hours.
The Southern Command earlier had sent a P-3 surveillance plane belonging to NASA.
The German-built diesel-powered vessel set sail on Monday from the southern port of Ushuaia enroute to its base in Mar del Plata, farther north in Buenos Aires province.
All terrestrial communications stations along the Argentine coast have been ordered to search for communications and listen to all possible frequencies of transmission by the submarine to try and make contact with the vessel.
Weather conditions in the region have made the search difficult, spokesmen said, with 6-8 meter (20-26 foot) waves prevailing there in recent days.