The snippets of costings provide only a small snapshot but the $US50 million ($54 million) spent on the two-year probe into Air France Flight 447 - the previous record - appears to have been easily surpassed after just four weeks.

Meanwhile, Malaysia's opposition leader, Anwar Ibrahim, has claimed the government is deliberately concealing information that would help to explain what happened to the missing flight.

Mr Anwar knew the pilot of flight MH370 that went missing on March 8 during a flight from Kuala Lumpur to Beijing. He called for an international committee to take over the Malaysian-led operation because ''the integrity of the whole nation is at stake''.

The biggest expense in the search has involved ships, satellites, planes and submarines deployed first in the South China Sea and the Malacca Straits, and then in the remote reaches of the southern Indian Ocean.

For example, HMAS Success, the Australian navy replenishment vessel deployed two weeks ago, costs about $550,000 a day to operate, a Defence spokesperson said.

HMAS Toowoomba was diverted a week ago to join the hunt for MH370 and has direct costs - fuel, supplies, wages of the crew - of $380,000 a day. Combined, the two vessels have cost more than $10 million while in the Indian Ocean, although Defence cautioned they were scheduled to be at sea anyway, so the additional expense to taxpayers of being re-routed was "estimated to be negligible".

Even so, the outlay can be included in a calculation of the resources devoted to the search for the jet and the 239 people on board.

It is also known that the United States Navy has allocated $US3.6 million for the deployment of a pinger locator and underwater drone on the vessel that will search for the plane's black box recorders.

On Wednesday, the Pentagon said that aside from the black box locators it had spent $US3.3 million on its ships and aircraft during operations to locate MH370.

Vietnam, reportedly, spent more than $US8 million searching for the plane in the South China Sea.

As many as 12 aircraft scour the seas for debris from the plane each day.

Geoff Dell, an air crash investigation expert from Central Queensland University, said the the cost of the aircraft flying daily 10-hour sorties would comfortably amount to $1 million a day. Over four weeks, a conservative estimate of the cost of the airborne search - excluding the US planes - would be $25 million so far.

The only other explicit cost figure is the $US5000 offered by the Malaysian government for the 227 passengers (not crew), which amounts to $1.25 million.

Taking the known costs and the estimate of the airborne search, it amounts to $53 million.

This would be only a small fraction of the expenditure so far given 26 nations have been involved in the search.

More than 40 navy vessels have been involved; China alone deployed seven vessels in the Indian Ocean.

Then there is the cost of the intelligence analysts, police and air crash investigators from Malaysia, the US, Britain and France, among others.

Air Chief Marshal (rtd) Angus Houston said on Friday he would give an overall estimate of the cost at a later date. ''It's a lot of money," he said.