Previous Coverage: Flight MH370: Kiwi oil rigger reports 'burning' plane (Mar 13)

See the latest developments here

In another day of confusion and contradiction, Malaysian authorities have not located flight MH370, which went missing six days ago with 239 people on board.

In overnight developments:

• Another "last" sighting of the missing plane revealed
• Last contact time confirmed
• Military "baffled" by lack of distress signal
• More countries join search effort
• Malaysian Airlines ‘aware’ of potential Boeing 777 fault
• China frustrated at lack of progress

Last sighting and contact
Confusion continues about the last known whereabouts of the Boeing 777-200, which was on a direct flight from Kuala Lumpur to Beijing.

In the latest twist, Vietnamese authorities have released an email by New Zealand oil rig worker Mike McKay that he had seen a burning plane in one piece at high altitude early on Saturday morning.

Mr McKay wrote an email to his employer, which Vietnamese officials confirmed they received but reportedly found nothing in the water.

"From when I first saw the burning (plane) until the flames went out (still at high altitude) was 10-15 seconds. There was no lateral movement, so it was either coming toward our location, stationary, or going away from our location," he wrote.

At yesterday’s acrimonious press conference in Kuala Lumpur, military officials said the last possible recording of flight MH370 was at 2.15am on Saturday morning 200 miles north west of Penang on Malaysia’s west coat.

Initially, authorities had said air traffic control lost contact at 1.20am as the plane was over the Gulf of Thailand on the northeastern side of the peninsula.

On Tuesday, the air force head, General Tan Sir Rodzali Daud, was reported as saying it was picked up by military radar at 2.40am over the Strait of Malacca on the western side – a statement he has since denied making.

Civil aviation chief Azharuddin Abdul Rahman said analysis of the defence radar showed an “indication of an air come back, hence that’s the reason why a search was conducted in Malacca and the Andaman Sea.”

Acting Transport Minister Hishammuddin Hussein pointed out that this was not a definite contact with the missing plane. “The primary data does not tell you about the aricraft per se. It requires corroboration and detailed analysis by experts.”

The investigators say they are still not sure whether the aircraft changed course and are “baffled” by why no distress signal was sent.

Search widened, India asked to join
The search area has been expanded still further to two areas either side of the Malaysia peninsula. The total search area now covers 27,000 square nautical miles – 12,425 square nautical miles in the Straits of Malacca and 14,440sq nm in the South China Sea. and involves 42 ships and 39 aircraft.

A dozen countries, now including India, Japan and Brunei, are deploying ships and 39 aircraft. An New Zealand Air Force Orion is based at Penang. India has been asked to search an area near the Andaman Sea.

Vietnam, which had halted its air search and scaled back a sea search while it waited for Malaysia to offer more detail, will resume with a stepped up operation, navy deputy commander Le Minh Thanh says.

Safety check directive
Malaysia Airlines insists the missing Boeing was airworthy before taking off but has declined to reveal whether it had been inspected for a known potential problem with the fuselage.

In November, US the Federal Aviation Administration warned airlines to look out for corrosion or cracking in the fuselage skin underneath the aircraft's satellite antennae.

This, the FAA said, could lead to a situation where the fuselage was compromised leading to possible rapid decompression as well as the plane breaking up.

Chinese frustration mounts
China has expressed more frustration at the slow progress of the investigation. A foreign minister spokesman says the release of the information has been “chaotic.”

China’s ambassador to Malaysia, Huang Huikang, sat in the front row seat at the press conference in Kuala Lumpur.