BIRD enthusiasts from around the world are joining forces to fight any proposal to develop the Hoo Peninsula and Cliffe Marshes for London's fourth international airport.

Organisers believe it will be one of the biggest protests ever known and they are determined to win.

Perry Haines, who has been appointed co-ordinator of the Royal Society for the Protection of Birds' campaign to protect the peninsula from becoming Britain's largest commercial airport, stressed: "We believe this will be the biggest conservation-led battle in European history."

The society's 1.2 million members, birdwatchers and European societies are joining the fight. "The local community will have a much louder voice than many people think," said Mr Haines.

He said pledges of support were already coming in to the RSPB's headquarters from as far afield as Italy and the Ukraine. Much of the threatened countryside is owned by the RSPB. It recently established new reserves at Cliffe Pools and also at Higham Marshes.

Most of the land on both sides of the peninsula is protected by Europe's highest environmental legislation. But this did not stop the British government allowing the construction of a car park on the Medway's Lappel Banks between Sheerness and Queenborough in the 1990s.

Eventually the European Court said the Government had acted illegally in ignoring the law intended to protect thousands of seabirds that lived and bred on the Medway estuary.

The airport proposal - five miles as the seagull flies from Lappel Bank - is expected to be published later this summer. But it has already been delayed a number of times.

The latest whisper from Whitehall is that the proposals are losing support from ministers. They are now thought to be backing an alternative plan to increase the use of Stansted airport in Essex.

Local birdwatchers are pledging their bird sightings as a way of objecting to the airport plan. So far almost 100 different species have been sighted from Hope Point - one of two viewing hillocks established for birdwatchers.

In the past week they have included two rare birds - a Montagu's harrier and a colourful European bee-eater.