CANBERRA - Assets for the search of missing Malaysia Airlines flight MH370 is expected to be increased in the coming days, Australian authorities said on Sunday.

Plane searches on Sunday could not locate debris spotted by Chinese satellites, the Australian Maritime Safety Authority (AMSA) said in a press briefing.

China said the object was 22 metres long and 13 metres, and spotted around 120 km "south by west" of potential debris reported by Australia off its west coast in the waters of the southern Indian Ocean.

The remoteness of the area, the Australian authorites said on Sunday, makes the search even more complicated.

Eight aircraft - 4 civilian and 4 military - are involved in Sunday's "visual" search, which will "go on into the late evening", they said, adding that visual search takes time and can be difficult.

They however emphasised that the search will continue "as long as there is hope".

The search for the missing plane entered Day 4 in the southern Indian Ocean on Sunday, a day after China revealed that new image captured early on March 18 spotted a large floating object in the same remote area.

Australian Prime Minister Tony Abbott said earlier on Sunday there was "increasing hope" of finding the missing plane, after unidentified debris including a wooden pallet, was spotted in the Indian Ocean search site.