The boom in cheap flights from West Midlands airports is costing the regional economy four times as much as it gains, a Friends of the Earth report claims.
Using data gathered from the Office for National Statistics, FoE researchers claimed domestic travellers using the region's airports were spending £1.7 billion more on their trips abroad than overseas visitors spend in the UK.
FoE said its research, published today, contradicted claims that airport expansion in the region is, overall, beneficial to the economy.
But a spokesman for Birmingham International Airport branded the report's conclusions "simplistic".
With 7,000 people working on site and thousands more in dependent businesses, he said, BIA was a major driver of the regional economy.
"Aviation is helping to mitigate the decline of traditional industry - excellent transport links attract new investors from abroad," he said.
"Expansion could create tens of thousands of jobs, connect the region to emerging economic giants, and see the Midlands as an economic
powerhouse rather than a monument to past glory".
FoE claimed that by the year 2020 the cost to the UK of airport expansion would top £30 billion.
Chris Crean, West Midlands region FoE campaigner, said the proposed expansion of Birmingham and Coventry airports would lead to an annual deficit to the region of £3.3 billion by 2020.
The FoE report said all regions of the UK except London received far less in revenue from foreign residents than the amounts spent abroad by Britons.
The increase in cheap flight sales was mainly due to better off people making more leisure trips on short breaks or visiting their second homes abroad, it claimed.
Mr Crean said the massive increase in cheap flights also went hand in hand with environmental neglect. " The growth is possible only because the aviation industry doesn't pay for its huge environmental impacts and is exempt from paying most taxes like fuel tax."
He added that increased aviation would make it virtually impossible for the UK or EU to meet pollution targets designed to prevent climate change.
"We know airport expansion is bad for the environment," he said.
"These figures show it is bad for aspects of the West Midlands economy, too. Local businesses are missing out on millions of pounds every year and airport expansion will make this worse."
The FoE research was undertaken as part of its climate change campaign, 'The Big Ask', which includes a challenge to the Government to bring in a new law which will cut carbon dioxide emissions by three per cent every year.
The report claims UK air travellers are spending £15 billion more abroad each year than overseas tourists are spending in Britain.
However, the British Air Transport Association rejected the findings.
"There is no evidence that airport expansion is bad for the economy.
"The industry itself supports 200,000 direct jobs and 600,000 indirectly," it said.
"About 18 million foreign visitors flew to Britain last year and this is set to grow, partly because of the expansion of regional airports."