Sir Richard Branson is backing a landmark legal challenge by environmental campaigners against a multimillion-pound luxury leisure complex which threatens to destroy some of the most eco-sensitive mangrove swamps in the British Virgin Islands (BVI), the paradise home of the British business tycoon.

The case, which is to be heard in full next year, is expected to have far-reaching consequences for the protection of the fragile Caribbean environment. Sir Richard, head of the Virgin group of companies, has paid for a team of barristers, led by the former chairman of the Bar Stephen Hockman QC, to fly to the group of islands and seek to stop plans to build a marina, five-star hotel and golf course in the British overseas territory.

The Branson family home is on Necker Island, which Sir Richard bought for £180,000 in 1979 and is located just over the water from Beef Island where the development is planned. At threat is one of the most important mangrove systems in the BVI, providing a vital home for hatchlings and juvenile fish, lobster and conch. Under the BVI government plans one of the golf holes is to be sited in the middle of the disputed area.

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The Virgin Islands Environmental Council (VIEC), a charity supported by Sir Richard and other interested groups, says it has brought the action to seek legal protection of the environment in the BVI for future generations.

A council spokesman said: "This is a landmark case that addresses a number of important issues which will impact on the future of environmental law and practice throughout the Caribbean. The outcome of this case will definitely impact the way other large projects currently under planning review are dealt with, leading to a more sustainable future for the BVI.

"The case will serve to define more clearly the government's responsibility in adhering to environmental laws when granting or refusing planning permission."

Last month, the case went to the East Caribbean Supreme Court, which rejected legal objections by the BVI government and the developers to the legal action going ahead. The action will begin in full early next year.

The campaigners hope the legal action currently underway will lead to a reversal of the planning permission and the redesignation of Beef Island as a Caribbean national park.

"We believe this will result in a more sustainable solution for Beef Island and set a healthy legal precedent for BVI and Caribbean development. At best the land may even become available for acquisition by the government with the critical areas being declared national parks, leaving the remainder available for sustainable development.

"By taking legal action, VIEC is ensuring the natural resources of the BVI are preserved for the benefit of future generations, that the government adheres to the procedures set out in law when granting planning permission, and that the people have a voice when addressing environmental issues that affect every citizen's wellbeing," the VIEC spokesman said.

Sir Richard recently announced plans for a new eco-resort on Mosquito Island, another of the British Virgin Islands, which will include 20 villas and a beachfront restaurant powered entirely by wind turbines and solar panels.

The BVI dispute is expected to be used to illustrate the case for an international environmental court which will be debated at a high-profile symposium at the British Library in London today. An International Court for the Environment (ICE) has been championed by Mr Hockman and has been given a cautious welcome by Gordon Brown. The Prime Minister told MPs earlier in the year that the first stage of moving towards an international environment court would be persuading all countries to agree to binding targets.