PERTH (AFP) - Australia said Wednesday cost was not a concern in the search for Malaysia Airlines Flight MH370, after the mini-sub plumbing the depths of the Indian Ocean for wreckage ended its ninth mission empty-handed.
Australia is leading the multinational search for the Boeing 777 which vanished on March 8 carrying 239 people, and is bearing many of the costs of the mission expected to be the most expensive in aviation history.
"There will be some issues of costs into the future but this is not about costs," Defence Minister David Johnston told reporters in Canberra.
"We want to find this aircraft. We want to say to our friends in Malaysia and China this is not about cost, we are concerned to be seen to be helping them in a most tragic circumstance."
China, whose citizens made up two-thirds of the passengers onboard the ill-fated flight, and Malaysia are among eight countries including Australia which have committed assets to the Indian Ocean search.
But with no confirmed sightings of debris from the flight on the surface so far, the search moved underwater nearly two weeks ago.
Australia's Joint Agency Coordination Centre (JACC), which is fronting the search, said Wednesday the device looking for the plane on the seabed had scanned some 80 per cent of its target zone without result.
The torpedo-shaped autonomous underwater vehicle called a Bluefin-21 is on mission 10 in the underwater search area, JACC said.
"Bluefin-21 has now completed more than 80 per cent of the focused underwater search area.
"No contacts of interest have been found to date." The device is searching an area at least 4,500m deep defined by a 10km radius around a detection of a signal believed to be from the plane's black box heard on April 8.
A visual surface search involving up to 10 military aircraft and 12 ships was also planned for Wednesday, despite suggestions last week that this aspect would be scaled down in coming days.
The visual hunt would cover an area totalling about 37,948 sq km some 855km northwest of Perth, JACC said.
Johnston said Australia was tracking the cost of the mission, and if the Bluefin-21 failed to spot wreckage the search would move into a new phase, but said Canberra was committed to the task.
"We move to the next phase which is a more intensive single sideband sonar type programme, I suspect, but let's take advice of the experts as to where we go forward," he said.
"But the enthusiasm, the dedication and commitment to doing what we've been doing has not waned, we are still out there, we're still flying, we're still on the surface, in our ships. We are still looking."
Johnston said Australia was talking with its partners about the assets needed for the next phase of the search for the plane which mysteriously diverted en route from Kuala Lumpur to Beijing.
"We are working that up now in consultation with our friends," he said.