The missing Beijing-bound Malaysia Airlines plane could not be traced for the fourth day Tuesday even as the Interpol ruled out a terror hand behind the incident.
As the multinational search operations continued Tuesday, the Chinese air force sent two military aircraft to bolster the search operations.
The aircraft set off from south China's Sanya City in Hainan Province, Xinhua reported citing the Chinese ministry of national defence.
They flew and searched for three hours Tuesday afternoon above the waters where the plane lost contact, according to the ministry.
Malaysia Airlines flight MH370 with 239 people on board vanished without a trace about an hour after taking off from Kuala Lumpur early Saturday. The Boeing 777-200ER was presumed to have crashed off the Vietnamese coast into the South China Sea.
The plane took off from Kuala Lumpur at 12.41 a.m. Saturday and was due to land in Beijing at 6.30 a.m. the same day. The 227 passengers on the flight included five Indians, 154 Chinese and 38 Malaysians.
Contact with the plane was lost along with its radar signal at 2.40 a.m. Saturday when it was flying over the Ho Chi Minh air traffic control area in Vietnam.
As of 3 p.m. Tuesday, five Chinese vessels, including two warships, had arrived and conducted search operations in the waters, but no suspected debris or objects have been found under water or on the water's surface.
Three more Chinese ships were expected to join the search team between Tuesday afternoon and Wednesday morning.
Dozens of ships and planes from around 10 countries are scouring the waters around flight MH370's last known location, but no solid clues have been found so far.
Meanwhile, the chief of the international police agency Interpol Tuesday ruled out a terrorist attack behind the disappearance of the passenger jet.
"The more information we get, the more we are inclined to conclude it was not a terrorist incident," said Lyon-based Interpol chief Ronald K. Noble, Xinhua reported citing local media.
In another development, one of the two passengers on board the Malaysia Airlines missing airliner travelling on a stolen passport has been identified as an Iranian, Malaysia's Inspector-General of Police Khalid Abu Bakar said Tuesday.
"The 19-year-old has been identified as Pouria Nour Mohammad Mehrdad and his intended destination was Frankfurt, Germany," the Malaysian Star quoted Abu Bakar as saying.
"When he did not arrive there, his mother contacted the authorities. She was aware he was using a stolen passport," he added.
The police are still investigating the identity of the second suspect travelling on a stolen passport on the missing flight and have not linked the Iranian teen to any kind of terrorist activity.
Meanwhile, Malaysia Airlines, in a website update Tuesday, said that search and rescue teams have expanded the scope beyond the flight path to the western peninsula of Malaysia at the Straits of Malacca.
“The authorities are looking at a possibility of an attempt made by MH370 to turn back to Subang. All angles are being looked at. We are not ruling out any possibilities,” it said.
“The mission is aided by various countries namely Australia, China, Thailand, Indonesia, Singapore, Vietnam, Philippines and the United States of America. The assets deployed to cover the search and rescue is extensive,” the statement said, adding that apart from the search in the sea, search on land in between these areas was also being conducted.
According to the airliner, the B777-200 aircraft that operated flight MH370 underwent maintenance Feb 23 this year, 12 days before this particular flight March 8 and there were no issues on the health of the aircraft. The next check was due June 19 this year.