A US official has claimed the mobile phone belonging to the co-pilot of Malaysia Airlines flight MH370 made contact with a network tower, half an hour after the missing plane veered off course.

The official claimed a signal from the phone of Fariq Abdul Hamid was picked up by a network tower in Penang, 250 miles from the location of the final signal emitted by MH370.

The official's assertions, reported by CNN, back up a theory that MH370 was flying low after diverting course in order to pick up a signal from a communications tower.

The claims also follow reports that Hamid tried to make a phone call after the plane vanished.

At present, Hamid is being treated as a suspect by authorities investigating the disappearance of MH370 somewhere over the Southern Indian Ocean.

Meanwhile, a submarine scouring the ocean floor for signs of the jumbo jet had to abandon its search when the water became deeper than 4,500m.

US Navy Captain Mark Matthews said: "It went to 4,500m and once it hit that max depth, it said this is deeper that I'm programmed to be, so it aborted the mission."

Elsewhere, a Russian newspaper has claimed the 239 passengers on board the plane when it vanished are alive and living in mud huts in Afghanistan.