Mr. Macri also said his government was in touch with the family members of the crew. “We share their concern and that of all Argentines,” he wrote. Pope Francis, who is Argentine, added his “fervent prayers” in a telegram on Saturday.
The British Navy’s assistance was notable given the war Britain and Argentina fought in 1982 over the Falkland Islands, which Argentina has long claimed as its sovereign territory. Both navies lost vessels, and nearly 1,000 military personnel died in the 10-week conflict.
The Protector, a British ice patrol ship, was expected to arrive at the search area from the Falkland Islands on Saturday afternoon, according to the British Embassy in Buenos Aires. In February, the ship was denied permission to dock in Buenos Aires, Argentine news media reported.
British officials have also put a C-130 Hercules aircraft stationed in the islands on standby.
A United States Navy P-8A Poseidon plane was expected to arrive in Argentina on Saturday night after being diverted from a counternarcotics mission in El Salvador.
In a statement, the American military said the plane, the Navy’s newest maritime patrol and reconnaissance aircraft, has “state-of-the-art sensors and communication equipment, allowing it to support a wide range of missions over large bodies of water, including subsurface search-and-rescue operations.” A NASA research plane had been dispatched late Thursday to assist in the search, the American Embassy in Buenos Aires said.
Chile has dispatched an aircraft to assist with the rescue mission, and Brazil, Uruguay, Peru and South Africa have also offered help.
The missing submarine was 240 nautical miles from the coast when it was last tracked. It was traveling from the Patagonian city of Ushuaia to Mar del Plata, in Buenos Aires Province, conducting a routine security patrol. Argentina’s three submarines are usually deployed to combat illegal fishing.
The submarine left Ushuaia on Nov. 8 and was scheduled to arrive in Mar del Plata on Sunday, according to the Navy.