The latest disappointing news came as Australia's prime minister said the hunt could continue indefinitely.
The crew of an Australian search plane spotted at least four orange objects that were more than two metres in size on Sunday, and the pilot dubbed the sighting the most promising lead in the search for Flight 370.
But yesterday Jesse Platts, a spokesman for the Australian Maritime Safety Authority, said the objects had been analysed and officials had confirmed "they have nothing to do with the missing flight".
It is a frustrating pattern that has developed in the hunt for the Boeing 777, which vanished on a night flight from Kuala Lumpur to Beijing on March 8 with 239 people aboard.
Search crews have repeatedly spotted multiple objects floating in remote patches of the southern Indian Ocean, only for officials to later confirm they are not linked to the missing plane.
Australian prime minister Tony Abbott has acknowledged the search was incredibly complex but said officials were "well, well short" of any point where they would scale back the hunt.