The aviation industry would begin to voluntarily improve aircraft tracking while mandatory standards were developed following the disappearance of Malaysia Airlines flight MH370, the UN aviation agency said on Tuesday.

The International Civil Aviation Organization gave no time frame for the binding standards on flight tracking to take effect.

This reflected the challenge of reaching an agreement with industry and governments globally on a longstanding problem, Reuters reported on Tuesday.

Nancy Graham, director of the ICAO's Air Navigation Bureau, said at a news conference: "A standard takes longer, it takes time. The process of cooperation is long, but it's important."

Despite the most intensive search in commercial aviation history, no trace of flight MH370 has been found since the Boeing 777-200 disappeared on March 8 during a flight from Kuala Lumpur to Beijing.

The plane is presumed to have crashed with 239 people on board in a remote part of the Indian Ocean about 1,600 km northwest of Perth, Australia.

Malaysian Prime Minister Najib Razak called for the ICAO to adopt real-time tracking of civilian aircraft.

"In an age of smartphones and mobile Internet, real-time tracking of commercial airplanes is long overdue," he said in a signed article in The Wall Street Journal.

He also called for planes' communications systems to be changed so they could not be disabled in mid-flight and to prolong the battery life of "black boxes", which record cockpit conversations and flight data.

Xu Ke, an aviation security researcher from Zhejiang Police College and a former pilot, said on Wednesday that airlines allow pilots to switch off the in-flight communication systems manually as a sign of trust toward the pilots.

Introducing measures such as forbidding pilots to shut off these systems manually and installing real-time cameras in cockpits would make crews feel that airlines did not trust them, Xu said.

A pilot for a Chinese airline, speaking on condition of anonymity, said that pilots like himself would feel offended if plane manufacturers made it impossible to turn communication systems off. "Does this mean they suppose all of us could be hijackers?"

The Civil Aviation Administration of China did not comment on Wednesday.

Wang Ya'nan, deputy editor-in-chief of Aerospace Knowledge magazine, said the ICAO's proposal came at the right time and should be considered seriously. "The industry can't afford to waste more time and just wait for the new standards. It should begin to improve its own tracking systems now."

After a short break, the Australian vessel Ocean Shield returned to the search area to continue the hunt for flight MH370, Xinhua News Agency reported.

Zhao Lei contributed to this story.