THE eco-warriors of Greenpeace are dragging their old adversary, Shell, back under the environmental spotlight by disrupting oil exploration in the Atlantic at maximum cost to the 17 companies working this part of the ocean.

Although the activists abandoned the granite out-crop of Rockall on Sunday night, they continue to harry radar boats from their dinghies.

Shell is reluctant to talk about the cost of disruptions, or how the industry might insure against it.

The reason for this reticence can only be guessed at. Perhaps Shell has simply had a bellyful of environmental protests this year. Its record in Nigeria and Peru has been attacked and it has faced a church-sponsored motion at its annual meeting demanding an environment director plus new codes of practice and independent audits.

But while Shell is up against Greenpeace at sea, Tarmac and other construction firms confront celebrity eco-warriors Swampy and his friends on land.

The cost of these confrontations run into hundreds of millions of pounds - although nobody will publicly put an exact figure on the losses.

But the meter ticks as Greenpeace drops swimmers in front of hi-tech high-maintenance radar ships almost 300 miles off Scotland; it whirrs as Swampy and other moles dig where engineers want to roll out roads.

Like Aids in the 1980s and cigarette-linked deaths in the l990s, the growing problem for industry will not go away.

"It is galling," says the director of the Civil Engineering Contractors' Association, Maurice Webb. "Most firms add the cost of the protests into the contract with the Highways Agency, so in the end the taxpayers meet the bill. And the protestors are by and large not taxpayers."

Companies are insured against damage to equipment and public liability insurance covers most potential injury. But in some cases, said Mr Webb, firms try to appease environmentalists by replacing badger runs and toad crossings.

He is gloomy about the future. "These people are Luddites. It does not matter where the road is, they will protest about it. This will hit the economy because the costs rise and less work gets done. No company will say how much it costs because they do not want to give fuel to the protestors."

"How," he asked, "do you insure against a Swampy?"

The answer, says broker Willis Corroon, is simple. You treat him like a site of historical significance or a rare species. "There is delay of completion insurance which protects a company against finding Roman temples where they are going to work, or against the lesser-crested newt, or whatever. It can cover you against Swampy as well.

"The cost of the premium depends on the project. It does not take an actuary to work out which projects Swampy is most likely to turn up at," a Willis Corroon spokesman said.

The Association of British Insurers admits there are few catastrophes in life that brokers and under-writers will not touch.

Even the debate about whether genetic testing should be required for life assurance is one the ABI regards as all but settled, as many firms believe the results are meaningless. This has been partly influenced by the developments in Aids research, the big insurance issue of the 1980s.

The ABI announced yesterday that it will be reviewing the industry's stance on people who have tested HIV positive. "Firms have heard a lot about these cocktails of drugs and they realise the situation has changed," said the spokesman.

Recent legislation forcing firms to provide equal access to insurance for disabled people was a sign that public opinion eventually has an impact on business - exactly what the eco-warriors are counting on.