The international team hunting for Malaysia Airlines Flight MH370 in the southern Indian Ocean has not found anything so far, with Australia's deputy prime minister saying the suspected debris may have sunk.

Warren Truss, who is acting prime minister while Tony Abbott is in Papua New Guinea, told reporters that "nothing of particular significance" had been identified in the search on Friday. 

Five planes were sent to look for objects that may be from the missing Malaysian jet, and an Australian official said the hunt would be extended for another day, according to AP news agency. 

Aircraft and ships have renewed a search in the Andaman Sea between India and Thailand, going over areas that have already been exhaustively swept.

Something that was floating on the sea that long ago may no longer be floating

Warren Truss, Australia's deputy prime minister 

Australian authorities said the first aircraft to sweep treacherous seas in an area about 2,500 km southwest of Perth was on its way back to base without spotting the objects picked out by satellite images five days ago.

"Something that was floating on the sea that long ago may no longer be floating," Truss told reporters in Perth, according to Reuters news agency. "It may have slipped to the bottom."

The search continues

But the search is continuing and Australian, New Zealand and US aircraft will be joined by Chinese and Japanese planes over the weekend.

"It's about the most inaccessible spot that you can imagine on the face of the earth, but if there is anything down there, we will find it," Australian Prime Minister Tony Abbott told reporters in Papua New Guinea.

"Now it could just be a container that's fallen off a ship. We just don't know, but we owe it to the families, and the friends and the loved ones to do everything we can to try to resolve what is as yet an extraordinary riddle."

India said it was sending two aircraft to join the hunt in the southern Indian Ocean. It is also sending another aircraft and four warships to search in the Andaman Sea, where the plane was last seen on military radar on March 8. 

In New Delhi, officials said the search in areas around the Andaman island chain was not at the request of Malaysian authorities coordinating the global search for the airliner.

"All the navies of the world have SAR regions," said Captain D.K. Sharma, an Indian navy spokesman, referring to search and rescue regions. "So we're doing it at our own behest. We're doing it on our own because the Malaysian plane is still missing."

Investigators suspect MH370, which took off from Kuala Lumpur for Beijing shortly after midnight on March 8, was deliberately diverted thousands of miles from its scheduled path.

They say they are focusing on hijacking or sabotage, but have not ruled out technical problems. 

The search for the plane also continues in other regions, including a wide arc sweeping northward from Laos to Kazakhstan.

Source: Al Jazeera and agencies