The hunt for the Malaysia Airlines jet has become the most expensive maritime search operation that China has been involved in, according to experts.

"China is the nation that has sent the largest group of ships and aircraft to the search," said Wang Ya'nan, deputy editor-in-chief of Aerospace Knowledge magazine.

"Therefore, we can be sure that the nation must have become the biggest spender in the operation, although no official figures are available."

Wang said the costs for fuel and wear on equipment are basically identical for China and Western nations, so it only takes some simple calculations to assess the amount spent by each nation based on the scale of their involvement in the search.

"As far as I know, the costs for wear are the biggest part of spending for flights involving fixed-wing planes and helicopters."

Cui Yiliang, a military observer in Beijing, said, "Without reliable information to support the calculation, the only guess I can make is that China would spend no less than any other nation.

"In addition, it is very difficult to estimate the costs for military personnel, which also comprise a considerable proportion of the overall expenditure."

China's military has not disclosed how much it has spent on the far-flung, monthlong search. Defense Ministry spokesman Geng Yansheng sidestepped a question on the issue at a news conference on March 27.

China, home to the majority of the 239 people on board the Boeing 777-200, has sent 18 ships, eight helicopters and three fixed-wing aircraft to various search areas.

Two Ilyushin Il-76 aircraft from the Chinese air force are taking part in the search from an air base near Perth.

Chinese newspaper Global Times quoted an unidentified military source as estimating that the fuel costs for keeping an Il-76 in the air are $10,000 an hour, excluding money spent on maintenance or accommodation for the crews.

Liu Jianping, a military expert, told the newspaper that the costs for vessels include fuel, water, food, medicine, salaries and subsidies for personnel. The vessels need constant maintenance and incur significant depreciation costs, he added.

The Chinese missile destroyer Haikou, which is taking part in the search, would cost up to $100,000 a day to operate, and the two amphibian landing crafts, Kunlunshan and Jinggangshan, would cost much more, the newspaper said.

At least $44 million has already been spent on the deployment of military ships and aircraft in the Indian Ocean and South China Sea by China, Australia, the United States and Vietnam, Reuters estimated in a report. This does not cover all the defense assets being used by countries including Britain, New Zealand and South Korea.

The figure already matches the 32 million euros ($44 million) spent in searches lasting several months spread over two years for an Air France jet that crashed into the Atlantic Ocean in 2009.

Last week, the US Department of Defense said it had already spent more than $3.3 million on the search and planned to nearly double its original $4 million budget.

Insiders say it is difficult to come up with a full estimate for the search, especially as many of the costs are a routine part of maintaining search-and-rescue capabilities.

zhaolei@chinadaily.com.cn