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.

Malaysia's New Straits Times, quoting an anonymous source, 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 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.

The police chief also clarified last week that passengers had not categorically been cleared since the investigation was ongoing.

Several theories have been put forward during the investigation including hijacking, a terrorist plot or a pilot gone rogue. But authorities are clutching 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 in the search area in South Indian Ocean.

But Australia's Joint Agency Coordination Centre said 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.

There were 12 aircraft and 14 ships combing a 57,506 square kilometer area on Sunday.

Australian Prime Minister Tony Abbott told Chinese media the search was narrowing, with "a high level of confidence" that the black box will be located.

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