Bosses at Gatwick airport have pledged to minimise the impact of a major expansion plan and have signed a landmark legal agreement.

The British Airports Authority plans to handle 40 million passengers a year at Gatwick by 2008, part of a development programme which will create 4,000 jobs.

But local communities have been campaigning against the plans on the grounds of increased air and noise pollution.

However, BAA yesterday took a major step towards ending protests and ruling out the need for a costly public inquiry by signing the new contract.

Agreed by West Sussex County Council and Crawley Borough Council, it binds BAA Gatwick to more than 40 legal obligations, all aimed at softening the blow of the airport's growth.

Gatwick currently handles 31 million people a year.

Proposals include action to reduce the impact of aircraft noise both in the air and on the ground, £10 million for local transport schemes, and a trust fund with a £100,000-a-year budget to boost community projects in areas most affected.

All 30,000 workers at the airport will be encouraged to use public transport while exhaust emissions and the amount of waste generated will be reduced.

BAA Gatwick managing director Janis Kong said: "The legal agreement we have signed represents a real contract with our local communities and avoids a lengthy public inquiry which only really benefits the legal profession.

"We want Gatwick to grow with the support and trust of our neighbours - and that means plans to develop the airport go hand in hand with plans for dealing with the environmental issues that we know cause people the most concern."