MH370 The Malaysia Airlines (MAS) chief executive said today the airline's role was to take care of the families of passengers who were on its missing jetliner and that it had curbed its advertising out of respect for their well-being.

MAS and the Malaysian authorities have faced heavy criticism, particularly from China, for mismanaging the search and holding back information. Most of the 239 people on board the missing flight MH370 were Chinese.

Chief executive Ahmad Jauhari Yahya ( right ) said it was "beyond any reasonable doubt the aircraft was lost".

On Monday, it will be 30 days since the jetliner lost communications and disappeared from civilian radar.

"Our role is basically to take care of the needs of the families and relatives," he told Reuters , saying no efforts were being spared to ensure their "emotional and financial health".

But he said he understood the families' frustration.

"The lack of answers is not giving comfort to anyone, especially for the families. The families want answers. Sometimes, answers are something we can't give."

MAS has given initial financial assistance of US$5,000 per passenger to their immediate families and put the families up in hotels in Kuala Lumpur and Beijing, but has been the target of angry protests in China.

Four weeks after the disappearance of the jetliner, searchers have launched the most intensive hunt yet in the southern Indian Ocean, trying to find the plane's black box recorders before their batteries run out.

Focus on pilots

Up to 10 military planes, three civilian jets and 11 ships will scour a 217,000 sq km patch of desolate ocean northwest of Perth near where investigators believe the plane went down on March 8 with the loss of all on board.

Ahmad Jauhari said the plane's disappearance would have an impact on the carrier's profits, although he did not give further details.

MAS, South-East Asia's fourth largest carrier by market value, was already loss-making before the incident. In 2013 it posted a net loss of RM1.17 billion, its third annual net loss in a row.

Authorities have not ruled out mechanical problems as a cause but say the evidence suggests Flight MH370 was deliberately diverted thousands of kilometres from its scheduled route from Kuala Lumpur to Beijing.

The Malaysian police have narrowed the scope of its investigations to the pilots and cabin crew after clearing the passengers.

Malaysia Airlines has also conducted its own probe into the pilots, Zaharie Ahmad Shah and Fariq Abdul Hamid.

"We didn't find anything suspicious (about the pilots)," Ahmad Jauhari said.

- Reuters