Search authorities now fear that the black box of the missing Malaysian Airlines plane has lost battery power, as no electronic signals have been recorded since April 8 when Australian ship Ocean Shield documented two sounds consistent with those of a flight data recorder.

A lack of black box pings could frustrate search efforts in the South Indian Ocean.

“No one should underestimate the difficulties of the task still ahead of us,” Mr Abbott told media in Beijing.

The search continues as unconfirmed reports in Malaysia’s New Straits Times suggest that the co-pilot of the plane, Fariq Abdul Hamid, made a call from his mobile phone after the plane went off the radar.

The Malaysian government has refused to confirm the reports.

“I cannot comment because, if it is true, we would have known about it much earlier,” Malaysian Transport Minister Hishammuddin Hussein told reporters yesterday.

A search investigator has also revealed to the Sunday Times that the missing aircraft was “thrown around like a fighter jet” in order to avoid radar detection after dropping from its cruising altitude.