Malaysian investigators are trawling through the backgrounds of the pilots, other crew members and ground staff who worked on a missing jetliner to find out why someone flew it far off course.
Background checks of passengers on Malaysian Airlines Flight MH370 have drawn a blank, but not every country whose nationals were on board has responded to requests for information, police chief Khalid Abu Bakar told a news conference in Kuala Lumpur on Sunday.
Malaysia has appealed for international help in the search for the plane across two corridors stretching from the shores of Caspian Sea to the far south of the Indian Ocean, Reuters reported.
Acting Transport Minister Hishammuddin Hussein said no groups have made any demands over the missing plane, even as he refuted rumours that the plane has landed somewhere.
He declined to comment on speculation that it could be a 9/11 style attack, saying only that "it is difficult to determine if it is hijack or terrorism".
Meanwhile, China spearheaded fresh criticism of Malaysia's handling of the incident, saying KL "squandered" precious time and resources by releasing vital information only a week after the jet vanished, AFP reported.
Malaysian Prime Minister Najib Razak said on Saturday that the KL-Beijing flight had been deliberately diverted away from the South China Sea, where the search effort had mostly focused till then.
"It is undeniable that the disclosure of such vital information is painfully belated," a scathing editorial by China's state-run Xinhua news agency said, noting the "excruciating" seven days it entailed for relatives of those missing.
In Singapore, Minister for Foreign Affairs and Law K. Shanmugam said that good intelligence is key to averting such incidents. Speaking on the sidelines of a community event on Sunday, he noted that the latest revelations were "quite chilling" and a "sharp reminder... that we cannot take anything for granted".
It is not practical to fully check all 50 million passengers passing through Changi Airport every year. "So the real answer is extremely good intelligence ahead of time, and close cooperation with others," he said.
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