SEPANG, Malaysia - The search for Flight MH370 entered the third day with the massive air and sea operation failing to unearth any trace of the plane.
Department of Civil Aviation director-general Datuk Azharuddin Abdul Rahman described it as an "unprecedented aviation mystery".
He said the authorities were exploring all angles in their investigations, including the possibility that the plane might have disintegrated in mid-air or exploded.
"We are not ruling out the possibility but the main focus is to find the plane," Azharuddin said at a press conference here yesterday.
Experts have described the absence of a distress signal from the plane as an indication that it suffered a sudden catastrophic failure or explosion. Hijacking has also not been ruled out.
"Such theories are being explored but we have to avoid speculating on the matter," Azharuddin said.
The United States has comprehensively reviewed spy satellite imagery for evidence of a mid-air explosion but found none, Reuters reported.
Quoting a government source, it described US satellite coverage of the region as "thorough".
"A total of 34 aircraft and 40 vessels from different nations are in the search and rescue operation," Azharuddin said.
A US Navy P-3 Orion aircraft capable of covering 2,414 sq km every hour was sweeping the northern part of the Straits of Malacca.
"Our aircraft are able to clearly detect small debris in the water, but so far it has all been trash or wood," Reuters quoted the US Navy's 7th Fleet spokesman, Commander William Marks, as saying.
Many rumoured sightings of supposed wreckage, included the purported tail of an aircraft in Vietnam waters, have been found untrue.
"We quickly sent vessels to the location but we discovered that it was merely logs tied together and it looked like a pontoon," Azharuddin said.
A yellow object that looked like a life raft off Tho Chu island was found by rescue helicopters and ships to be moss-covered trash.
The Malaysian Maritime Enforcement Agency's eastern region enforcement chief, Datuk Nasir Adam, said tests on a sample of the oil slick found off the Kelantan coast showed that it was not from the missing Malaysia Airlines flight.
On airport security, Azharuddin said there were five passengers who checked in for the flight but did not board the plane.
The baggage of all the five were removed in accordance with ICAO requirements, he said.
Azharuddin said it could be a long time before the black box of Flight MH370 is found.
He said there was no timeframe for the search and rescue operation.