International police agency Interpol says at least two passports recorded as lost or stolen in its database were used by passengers to board the Malaysia Airlines flight that disappeared after taking off from Kuala Lumpur on Saturday morning.

The agency added that it was "examining additional suspect passports". Interpol said no checks of its database had been made by any country on the stolen Austrian or Italian passports between the time that they were reported lost and the departure of the flight.

Meanwhile, rescue teams from Vietnam continue to search the waters of the South China Sea for the missing plane. Vietnam said search planes had found suspected fragments of the missing jetliner.

Earlier, a Vietnamese military official said two large oil slicks off the country's southern tip had been spotted, but later disappeared. A new oil slick was reported about 80 kilometers southwest of the first two. But the official said it was probably a result of the first two slicks spreading and drifting.

A Vietnamese rescue plane is conducting a search around Vietnam's Tho Chu Islands, along with rescue crews from China, Malaysia, and Singapore.