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.
Chinese Premier Li Keqiang said as long as there remains a "glimmer of hope" China will not stop the search for the missing Malaysian Airlines jet.
"This is an international and large-scale search operation involving many countries," he said. "The Chinese government has asked the relevant party to enhance coordination, investigate the cause, locate the missing plane as quickly as possible and properly handle all related matters."
It is the sixth day of the search for the flight, which went missing flying from Kuala Lumpur to Beijing and China has dispatched multiple aircraft, ships and satellite in the multinational search mission.
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.