PHU QUOC ISLAND, Vietnam -- Search teams had found no trace of a missing Malaysian jetliner almost three days after it lost contact with air traffic control, a senior Vietnamese official said Monday.

A life jacket-like object, spotted at sea by a commercial plane from Hong Kong earlier in the day, turned out to be unrelated to Malaysia Airlines flight MH370, Deputy Transport Minister Pham Quy Tieu said.

Vietnam would continue to expand the search area and release reports on the progress, said Tieu, who was appointed Sunday to command search and rescue operations from Phu Quoc island in southern Vietnam.

He added that search and rescue vessels from China, Malaysia, Singapore and the United States had been allowed to enter Vietnam's territorial waters to help with the search.

Vietnam had sent four aircraft and 12 ships to the search area and asked private fishing boats to inform the government of any information that might help locate the missing plane, Tieu said.

Huynh Quang Hung, a local government official on Phu Quoc island, said sufficient medical supplies and devices had been prepared for emergency services.

The local government would ensure the safety of foreign journalists and families of the passengers of the missing plane, he said.

Flight MH370, carrying 12 crew members and 227 passengers, including 154 Chinese, left Kuala Lumpur International Airport for Beijing and lost contact with air traffic control Saturday while passing through the Ho Chi Minh air traffic control area.