Campaigners are trying to block airport expansion at Heathrow

The Royal Borough of Windsor and Maidenhead has donated �5,000 towards the action brought against the government by two London boroughs.

The hearing, likely to take place in October, could cost Wandsworth and Hillingdon councils at least �100,000.

The leader of Windsor and Maidenhead council said there were very serious implications for Berkshire residents.

Other councils around Heathrow whose residents may be affected by a third runway have contributed to the fund.

'Very important judgement'

Wandsworth and Hillingdon councils are challenging a government white paper which contains proposals for airport expansion legislation.

Plans for expansion at Stansted and Luton airports are also being challenged.

Council leader Mary Rose Gliksten said: "Residents are already plagued by aircraft noise, both day and night, and the possibility of a third runway with its implied increases in flights over our borough would be a step too far.

"The council is in full support of the Wandsworth and Hillingdon court action and I believe we should show this in a tangible way that helps pay for the legal costs in what could be a very important judgement."

If the councils win, the government could be forced to re-run the consultation period that led to the proposals for legislation.