Birmingham International Airport has exaggerated future passenger figures and overstated the economic benefits of expansion, countryside campaigners claimed.
As the consultation into the airport expansion came to a close last week, the Campaign to Protect Rural England questioned forecasts of three and a half times as many passengers at Birmingham by 2030 outlined in the airport's draft master plan.
It warned the growth of the airport would be unsustainable, leading to more greenhouse gas emissions, congestion on roads and railways and pollution and noise in the surrounding area. The CPRE said with the present runway less than half full, it did not believe a second runway was justified and the case for extending the existing runway had not been adequately made.
BIA plans to extend the current runway by 2012 and build a second runway and third terminal around 2020. The £1.5 billion development is designed to meet a predicted tripling in passenger demand over the next 25 years.
The Institute of Directors has urged the airport to put plans for a second runway on ice and focus its efforts on bringing forward the planned runway extension in time for the London Olympics in 2012.
A Government White Paper in 2003 endorsed the important role of regional airports in supporting regional economic development and regeneration, increasing regional choice for air travel, and relieving congestion in the South-east.
Gerald Kells, regional policy officer for CPRE West Midlands, said the economic benefits of expanding BIA had been overstated, with the costs of doing so ignored. He said the proposals would double the area occupied by the airport and take a huge slice out of the green belt.
Further development such as homes, offices, hotels, warehousing, shops and schools needed to support the expansion would greatly increase the damage.
Mr Kells said: "Birmingham International Airport provides an important service to the West Midlands, but we should not give it a blank cheque for unlimited expansion at the cost of the environment. We favour more moderate, balanced growth which will still support the regional economy but reduce damage to the environment and enable roads and public transport to take the strain."
John Morris, BIA's head of corporate affairs, described the CPRE's claims as "ill-informed".
He said: "For instance, they seem to imply that we should use the existing runway to full capacity.
"This would lead to a massive increase in night flights, over and above existing quotas - something that we have promised we will never do."