The Argentine navy is stepping up its search in the South Atlantic for a 44-crew submarine that has been out of radio contact for three days. <br/><br/>President Maurico Macri said all national and international resources are being deployed to help find the San Juan as quickly as possible. <br/><br/>A Nasa research plane has joined the search for the vessel. Britain and countries in the region have offered help after it disappeared 430 kms off the coast.<br/><br/>The diesel-electric submarine was returning from a routine mission to Ushuaia, near the southern-most tip of South America, to its base at Mar del Plata, south of Buenos Aires. <br/><br/>Its last contact with the navy command was on Wednesday morning. An Argentine destroyer and two corvettes are conducting a search around the area of the sub's last known position off the south-eastern Valdez peninsula. But so far there are no clues about its whereabouts. <br/><br/>The rescue operation has been formally upgraded to a search-and-rescue procedure after no visual or radar contact was made with the submarine.

The Argentine navy is stepping up its search in the South Atlantic for a 44-crew submarine that has been out of radio contact for three days. <br/><br/>President Maurico Macri said all national and international resources are being deployed to help find the San Juan as quickly as possible. <br/><br/>A Nasa research plane has joined the search for the vessel. Britain and countries in the region have offered help after it disappeared 430 kms off the coast.<br/><br/>The diesel-electric submarine was returning from a routine mission to Ushuaia, near the southern-most tip of South America, to its base at Mar del Plata, south of Buenos Aires. <br/><br/>Its last contact with the navy command was on Wednesday morning. An Argentine destroyer and two corvettes are conducting a search around the area of the sub's last known position off the south-eastern Valdez peninsula. But so far there are no clues about its whereabouts. <br/><br/>The rescue operation has been formally upgraded to a search-and-rescue procedure after no visual or radar contact was made with the submarine.