ENVIRONMENTAL pressure group Greenpeace is to dispatch its flagship campaign vessel to St Kilda to highlight its concern over an environmental threat to the island from offshore oil companies, it was announced yesterday, writes Lesley Millar.

The move followed a report by an international wildlife watchdog claiming that Scotland's remotest island group and most spectacular seabird sanctuary is at ''high risk'' from developing oil giants.

Despite Government reassurances that extensive oil development in the north east Atlantic will have ''minimal'' environmental impact, the respected Swiss-based International Union for the Conservation of Nature (IUCN) has recommended placing St Kilda on a danger list of threatened World Heritage Sites.

The IUCN's report is highly embarrassing to the Scottish Office, which it criticises for failing to respond to earlier fears raised by the Unesco World Heritage Committee last December.

Greenpeace said the Rainbow Warrior would arrive later this month and would carry out the first three-dimensional mapping of seabed life around St Kilda. The survey will focus around the north coast of the island, which is considered to be most at risk.

St Kilda, which lies 110 miles off the western coastline and 40 miles beyond the Outer Hebrides, is one of 17 British sites to be classified as a World Heritage Site, placing it in the same category as the Great Barrier Reef and the Taj Mahal. It is the only natural British site on the list.

The islands have not been inhabited since 1930, when the last 36 remaining residents were evacuated to the mainland at their own request, but are home to more than 400,000 seabirds, including puffins, fulmars, and a quarter of the world's population of gannets.

The waters around St Kilda are a migratory route and home to at least 22 species of whales and dolphins, including the very rare blue whale, the world's largest mammal.

The latest of 142 exploration sites to be licensed in the proximity of St Kilda, belonging to US company Marathon Oil, is only 70 miles from the shore.

The IUCN's report backs environmentalists' concerns that potential oil spillages carried by wind or wave could reach St Kilda's beaches within 48 hours.

The report was welcomed by both Greenpeace and the National Trust for Scotland, which owns St Kilda.

Trust director Trevor Croft said it did not believe current regulations regarding oil spillage were strong enough, or adequately followed or enforced, and was particularly concerned about the threat to birds.

Mr Rob Gueterbock, a Greenpeace campaigner, said: ''The IUCN's damning report undermines the credibility of the Scottish Office when they say there is a 'minimum' risk to St Kilda.''

Nevertheless, Scottish Ministers still maintain that the developments present no real threat to St Kilda. A spokesman at the Department of Trade and Industry said: ''The oil spill risk assessment for the closest existing development, at Foinaven, demonstrates oil is highly unlikely to reach the isle of Lewis - and St Kilda is 100 miles further than that.''