A Swiss billionaire has stepped in to save plans to create the world's largest marine reserve from public spending cuts.
British ministers are in talks over a £3.5 million deal for America's Cup-winning yachtsman Ernesto Bertarelli to fund the policing of the zone around the UK-owned Chagos Islands.
The Marine Protected Area (MPA) will cover some quarter of a million square miles of sea around the archipelago in the Indian Ocean and include a "no-take" reserve banning commercial fishing.
It was approved by then foreign secretary David Miliband in April amid complaints that the Government failed to take account of the needs of the territory's exiled inhabitants.
The Chagos have been the subject of a long-running controversy as the islanders exiled to make way for the Diego Garcia US airbase continue a legal fight for the right to return home.
Fears had been raised, however, that the project could be scrapped without private funding to offset the £750,000 a year set to be lost in fees for lucrative tuna fishing licences.
But campaign group the Blue Marine Foundation said it had secured the backing of the Bertarelli Foundation to provide the necessary financial backing - with ministers agreeing the deal in principle last week and detailed contracts now being drawn up.
Italian-born entrepreneur Mr Bertarelli and his British wife Kirsty - a former Miss UK - are believed to share a £6 billion fortune based on pharmaceuticals and biotechnology.
The deal includes the provision of a patrol boat - named the Pacific Marlin.
Blue Marine said a £1.5 million deal to provide fuel for the patrols had been negotiated separately by the Pew Foundation, part of the Chagos Environmental Network, and the Pentagon.