Thailand's space agency has reported satellite images showing 300 items floating in the southern Indian Ocean that could be debris from the ill-fated Malaysian Airlines flight.
The discovery was reported less than 24 hours after the Malaysian government revealed 122 objects had been seen about 2557 kilometres from Perth, ranging in length from one metre to 23 metres.
In its reports on the latest find on Thursday, AFP said the Geo-Informatics and Space Technology Development Agency had captured satellite images of the 300 objects scattered over an area about 2700 kilometres southwest of the West Australian capital.
They ranged from two to 15 metres in size.
"We cannot - dare not - confirm they are debris from the plane," the space agency's executive director Anond Snidvongs said.
The news came as the last search plane returned to Perth for the day after efforts were largely thwarted by bad weather, the second time this week.
However, five vessels including the HMAS Success and four Chinese ships continued to visually scour the waves.
Captain Mike MacSween, a Royal Canadian Air Force pilot on exchange with the RAAF, piloted the only Australian P3 Orion to make it to the search area before the weather closed in.
Capt MacSween said the plane's crew searched the area for about two and a half hours, mainly at a height of around 500 feet, but didn't see anything of note.
"It was definitely not ideal for visual search conditions," he said.
"The visibility was anywhere between five miles and basically zero."
He said the plane flew as low as 200ft (61m) in an attempt to keep sight of the surface.
HMAS Success Captain Allison Norris told CNN that no objects related to the missing Boeing 777 had been seen.
Capt Norris said weather conditions were expected to deteriorate for up to 48 hours, and also revealed the pieces of debris being sought were so small and close to the water line that the vessel's radars could not pick them up.
"We are very reliant on lookouts who use binoculars and night vision devices to scan the horizon and scan the area around our ship," she said.
"It is very cold so we rotate the lookouts through every hour."
In Malaysia, officials again sought to assuage the angry relatives of the flight's 153 Chinese passengers.
Some of the relatives of the Chinese passengers have expressed outrage that Malaysia essentially declared their loved ones dead without recovering a single piece of wreckage.
At a hotel banquet room in Beijing on Wednesday, a delegation of Malaysian government and airline officials were met with scepticism and even ridicule when they explained what they knew to the family members.
Some questioned how investigators could have concluded the direction and speed of the plane.
One man said he wanted to pummel everyone in the delegation.
Meanwhile, a US-based law firm filed court documents that often precede a lawsuit on behalf of a relative of an Indonesian-born passenger.
The filing in Chicago asked a judge to order Malaysia Airlines and Boeing to turn over documents related to the possibility that "negligence" caused the plane to crash, including any papers about the chances of "fatal depressurisation" in the cockpit.
And in Washington, FBI chief James Comey told lawmakers that experts were working "literally round the clock" to finish their analysis, in the hopes that the data could provide clues to what happened.
- AAP, AFP