Thanks from China over plane effort

Chinese Premier Li Keqiang has thanked Australia for its "tremendous support" in searching for Malaysia Airlines flight MH370.

The thanks came in a telephone call with Prime Minister Tony Abbott on Wednesday before the arrival in Perth of Malaysian Prime Minister Najib Razak.

Mr Abbott updated Premier Li on the search effort and expressed his condolences for the loss of Chinese citizens on the aircraft.

Premier Li expressed his sympathies to the families of the six Australian passengers lost and expressed his appreciation of Australia's "tremendous support".

Mr Abbott told Premier Li Australia would welcome and support any family members who wished to come.

Up to eight planes and nine ships will assist in Thursday's search for the aircraft.

The Australian Maritime Safety Authority has determined a search area of about 223,000 square kilometres, 1680 kilometres west northwest of Perth.

The search area is being refined by a team comprising analysts from Malaysia, the United States, the UK, China and Australia.

Mr Abbott, who will visit China next week, will meet Premier Li at the Boao Forum.

China highly valued its relationship with Australia and hoped to take it to a new level during the visit, Premier Li said.