Malaysia Airlines (MAS) has told relatives of passengers on flight MH370 to "expect the worst" as the search for the missing plane stretches to more than 36 hours.
"But I want to emphasise that as we have not found the aircraft, we will continue trying our best to search for the airplane," said Mr Ignatius Ong, spokesman of the airlines, at a press conference at a Beijing hotel on Sunday.
He said both naval and air forces are working to locate the plane.
MAS is working with the Malaysian embassy in Beijing to facilitate visa applications for those who want to fly to Kuala Lumpur, he said, adding that the next of kin of all passengers have been contacted.
Mr Ong declined to answer questions about the number of passengers on the flight who were said to be using fake passports.
Media reports have said there were four such passengers.
But in Malaysia, the authorities said on Sunday they have CCTV recordings of two passengers who were said to have used false passports to board the Beijing-bound flight.
Department of Civil Aviation director-general Azaruddin Abdul Rahman said there were only two such passengers, not four as earlier reported by the media.
Earlier, two men - an Italian and an Austrian - had confirmed that they were not on the flight despite their names appearing on the manifest. Their passports were reported stolen in Thailand up to two years ago.
Mr Ong also said that the FBI has not contacted the Beijing command centre.
US media reports have said the FBI is sending agents and technical experts to assist a team probing the disappearance of the plane.
On rumours that one of the passengers' phone rang when a relative dialled the number, Mr Ong said this information has been passed on to the Malaysian and Chinese authorities. But he added that he has personally called the number and there was no ringing tone.
MAS also told family members that they had tried calling the mobile phones of the flight crew but there was no answer although there was a ringing tone.
Meanwhile, about 100 family members have signed a petition claiming that MAS is "hiding the truth" over the missing plane.