REUTERS/Paul Kane/Pool
The objects were spotted in waters roughly 2,500 kilometres (1,550 miles) southwest of Perth, Kyodo and Jiji news agencies said.
Japan's Cabinet Satellite Intelligence Center's study showed objects up to eight metres (26.4 feet) in length and four metres wide in images captured by a satellite between 9 am and 3 pm (0000 GMT and 0600 GMT) Wednesday, Kyodo said.
A government source said they could be wreckage of the missing plane since they were found in an area overlapping the sites where debris had previously been spotted, according to the agency.
Jiji quoted a government official as saying the floating objects were "highly likely" to be part of the plane.
Japan had handed the information to Malaysia, the reports said.