BEIJING - While China's airport building boom during the past five years has boosted local economies, it has also led to the take-off of a series of graft and environmental problems, the country's top audit body said on Monday.

Ten airport projects across the country cost taxpayers 159 million yuan ($24 million) in false accounting and tax avoidance, the National Audit Office (NAO) said.

And a total of 23 airports spent 1.94 billion yuan on projects that were not open to public tendering, even though they were supposed to be, the office said, implying contracts were open to abuse.