KUALA LUMPUR: Malaysia is investigating four names on the flight manifest of an airliner that vanished with 239 people aboard, as it probes a possible terror link, the transport minister said Sunday.

The comments by Hishammuddin Hussein looked set to fuel speculation over whether a security breach or hijack may have played a role in what would be Malaysia's worst-ever aviation disaster.

Those fears arose after it emerged Saturday that two people boarded the missing Malaysia Airlines flight 370 with stolen European passports.

Hishammuddin, when asked to confirm Malaysian media reports that another two suspect passengers had been identified, said: “All the four names are with me.”However, he declined to offer details, saying authorities were examining “the entire manifest”.

A civil aviation official later clarified that authorities still so far believe only two passengers had used stolen passports and were examining CCTV footage of them.

“There are only two passengers on record with false passports,” department of civil aviation director general Azharuddin Abdul Rahman said.

“We have CCTV recordings of the two passengers. The recordings in the CCTV are now being investigated.”

”There is no four people, only two.”

Flight 370 went missing somewhere between the coasts of Malaysia and Vietnam early Saturday morning en route overnight from Kuala Lumpur to Beijing.

Hishammuddin said Malaysia was in touch with the counter-terror agencies of the US and other countries. “On the issue of the passports, I'm in touch with the international intelligence agencies,” he said.

“At the same time our own intelligence has been activated, and of course, the counter-terrorism units... from all the relevant countries have been informed.”Asked whether Malaysia believes the plane was hijacked, he said: “We are looking at all possibilities.”Hishammuddin, who previously was home minister in charge of state security, confirmed US media reports that the Federal Bureau of Investigation (FBI) was dispatching personnel to Malaysia.

“I have also spoken to international intelligence agencies to assist us, and I'll be meeting them later this afternoon,” he said, adding the FBI was among them.

Vietnam has said its search planes have spotted oil slicks in seas near the plane's last known position, but no other debris or wreckage has yet been found.

Hishammuddin confirmed a slick had been spotted but said he had no further news.

There has been no terrorist claim or other evidence of a hijack or attack.

When asked how people could have boarded the plane with stolen passports, he responded: “This has to be... investigated.”

”We haven't even decided on whether there is a security risk at all. We have to not jump the gun,” he said.

“If it's a security risk, let's see where the lapse is. I have nothing to hide.”