Beijing, March 11 (RHC)-- A multi-country effort is in its fourth day of searching for a commercial airliner that disappeared en route from Malaysia to China without a trace.

Malaysia Airlines Flight 370 was carrying 239 people on board. Suspicion of a hijacking has grown after it emerged at least two passengers were traveling on stolen passports.

A team of ships and aircraft has been scouring the waters between Malaysia and Vietnam, where the plane last made contact, as well as the Strait of Malacca, on the opposite side of the Malaysian Peninsula. No debris has been found so far. A large oil slick was spotted in the sea south of Vietnam, but its source has yet to be confirmed.