An "electronic ping" was picked up from the Malaysia Airlines flight by satellites after the plane lost contact with ground control, Reuters reports. Meanwhile, US officials have been given an "indication" the plane crashed into the Indian Ocean.
A young Iranian man travelling using stolen passport on the missing Malaysia Airlines flight has been named as Pouria Nour Mohammad Mehrdad who is "not likely to be a member of a terrorist group".
Officials said the 19-year-old was probably migrating to Germany.
Channel 4 News Asia correspondent John Sparks tweeted a CCTV image of the man:
Malaysia Airlines flight MH370 went missing on Saturday with 239 people on board in what Malaysia's civil aviation chief called an "unprecedented mystery".
Investigators have widened the search for the missing plane as the operation entered a fourth day.
A mother has described her frustration as she waits for answers on the fate of her missing son who is on board the missing Malaysia plane.
Malaysia's military believes a jetliner missing for almost four days turned and flew hundreds of kilometres to the west.
The wife of a passenger travelling on the missing Malaysia Airlines flight has spoken of her struggle to cope as she waits for news.