PHU QUOC ISLAND (REUTERS) - Vietnam has scrambled rescue helicopters to check a "yellow object" floating in its waters that rescue teams suspect could be a life raft from a Malaysian plane that went missing with 239 people aboard, a minister said on Monday.

A Vietnamese jet had seen the object earlier on Monday but was unable to get close enough to determine what it was, Pham Quy Tieu, Vice Transport Minister and deputy head of the country's rescue committee, told Reuters.

The Civil Aviation Authority of Vietnam said on its website searches were being conducted about 140 km south-west of Tho Chu island, which is located about 200 km off the coast of southern Vietnam.