KUALA LUMPUR (AFP) - Malaysia on Sunday rejected claims that phone calls were made from flight MH370 before it vanished, but refused to rule out any possibility in a so far fruitless investigation into the jet's disappearance.
Australia's Joint Agency Coordination Centre, which is leading the search, said on Sunday that another 24 hours had passed without a confirmed signal, increasing fears that batteries in the beacons attached to the plane's two black boxes may now have run flat.
The New Straits Times, quoting an anonymous source, had reported Saturday that co-pilot Fariq Abdul Hamid made a call which ended abruptly, possibly "because the aircraft was fast moving away from the (telecommunications) tower".
There had also been unconfirmed reports of calls by the Malaysia Airlines plane's captain Zaharie Ahmad Shah before or during the flight.
Malaysian Transport Minister Hishammuddin Hussein told reporters on Sunday that authorities had no knowledge of any calls from the jet's cockpit.
"As far as I know, no," he said when asked if any calls had been made.
However, he added that he did not want to speculate on "the realm of the police and other international agencies" investigating the case.
"I do not want to disrupt the investigations that are being done now not only by the Malaysian police but the FBI, MI6, Chinese intelligence and other intelligence agencies," he said at a press conference in Kuala Lumpur.
Mr Hishammuddin also said no passenger on the plane had been cleared in the criminal investigation into the fate of the flight, clarifying an earlier indication from Malaysia's police chief.
"The Inspector-General of Police said at that particular point in time there is nothing to find suspicion with the passenger manifesto but... unless we find more information, specifically the data in the black box, I don't think any chief of police will be in a position to say they have been cleared."
The police chief also clarified last week that passengers had not categorically been cleared since the investigation was ongoing.
Pilots Fariq and Zaharie have come under intense scrutiny since the plane vanished en route from Kuala Lumpur to Beijing with 239 people on board on March 8, with still no clue as to the cause of the disappearance.
Investigators last month indicated that the flight was deliberately diverted and its communication systems manually switched off as it was leaving Malaysian airspace, triggering a criminal investigation by police which has revealed little so far.
Several theories have been put forward, including hijacking, a terrorist plot or a pilot gone rogue. But authorities are grasping at straws as to the fate of the plane without crucial data from the jet's "black box" flight recorder, which has yet to be located, and without any wreckage.
Several sonic 'pings' which authorities have said are consistent with a black box have been detected by ships in the search area in the remote southern Indian Ocean, off the west coast of Australia.
But Australia's Joint Agency Coordination Centre said on Sunday that another 24 hours had passed without a confirmed signal, increasing fears that batteries in the beacons attached to the plane's two black boxes may now have run flat.
The last pings were detected on Tuesday.
There were 12 aircraft and 14 ships combing a 57,506 square kilometre (22,200 square mile) area on Sunday, 2,200 kilometres northwest of Perth. They include Australia's Ocean Shield which is using a US Navy towed pinger locator to pick up the hoped-for black box signals.
Australian Prime Minister Tony Abbott told Chinese state television the search was narrowing.
"We're narrowing down the undersea area where we believe now with a high level of confidence the black box recorder from MH370 is located," he said in an interview Saturday.
"The surface search area is still about 50 kilometres by 40 kilometres," he added, saying that the object of the current hunt was to detect as many transmissions from the "fast fading" black box beacons.
"When we think we've got everything we can through this means we will deploy the submersible," he said.
"By that stage we hope we will have narrowed down the search area on the seabed to as little perhaps as a square kilometre."
Despite his confidence that the signals so far detected are from MH370, Abbott reiterated the huge challenges.
"I stress the difficulty of the task and the danger of false hope and unrealistic expectations."