BEIJING (REUTERS) - 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.

China's ambassador to Malaysia met Malaysia's foreign minister on Monday, Foreign Ministry spokesman Hong Lei said at a regular briefing in Beijing.

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 777-200ER for clues as to why someone on board flew it perhaps thousands of miles off course.

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.