Malaysia must "immediately" expand and clarify the scope of the search for a Malaysia Airlines jetliner that disappeared with 239 people on board, the Chinese Foreign Ministry said on Monday in a statement posted on its website.
Meanwhile, Foreign Ministry spokesman Hong Lei said at a regular briefing in Beijing that China's ambassador to Malaysia met Malaysia's foreign minister on Monday.
No trace of the plane has been found more than a week after it vanished but investigators believe it was diverted by someone with deep knowledge of the plane and commercial navigation.
Satellite data suggests the plane could be anywhere in either of two vast arcs: one stretching from northern Thailand to Kazakhstan, or a southern arc from Indonesia into the Indian Ocean west of Australia.
"Of course search and rescue efforts have become even harder now, and the area is much bigger," Hong said. "We hope that Malaysia can provide more thorough, accurate information to countries participating."
Hong declined to comment when asked if China is checking into the backgrounds of the Chinese passengers on board in search of suspicious histories. He declined to say whether China is searching over Tibet and the western region of Xinjiang for the jet, or whether China has ruled out that the plane entered its airspace.
About two-thirds of the passengers on board the flight were Chinese.
Malaysian investigators are trawling through the backgrounds of the pilots, crew and ground staff who worked on the missing Boeing <BA.N> 777-200ER for clues as to why someone on board flew it perhaps thousands of miles off course.