'Low-flying airplane'
Meanwhile, Thailand's air force said on Tuesday a re-examination of its radar data found what may have been the plane travelling west towards the Malacca Straits at 01:28 Malaysia time, shortly after it lost contact with air traffic controllers.
This would be consistent with Malaysia's military radar, which spotted the plane over the Malacca Straits - the opposite direction from its planned flight path - early on 8 March.
Thai air force spokesman Montol Suchookorn said that the plane did not enter Thai air space, and he could not confirm whether it was flight MH370.
Thai radar later spotted the plane heading north and disappearing over the Andaman Sea, AFP reported, citing the spokesman.
The Thai military had previously said it had not detected any sign of the aircraft.
In another development, police in the Maldives are investigating reports that residents saw a "low-flying airplane" above Kuda Huvadhoo island the day the plane vanished, AFP news agency reports.
Many leads and sightings of possible debris pursued so far have proven not to be linked to the plane.
The entire search area is now 2.24m square nautical miles (7.68m sq km), Malaysian authorities said.
Several countries, including Australia, the US, New Zealand, Korea, Japan and the UAE have committed planes and ships to the search and rescue effort.
Relatives of the 153 Chinese passengers on board the plane have become increasingly frustrated with the lack of information.
Wen Wancheng, whose 33-year-old son Wen Yongsheng was on the plane, told the BBC: "We think the Malaysian government is not doing enough work.
"The airline hasn't given us a satisfactory answer and the Malaysian officials are not here with us. If this situation continues, we will consider taking actions such as staging a protest.