The 'dam-busters' at 450ft: Eco-warriors climb the millennium wheel to stage sky-high protest at river projects

Two international ecoprotesters were clinging to the top of the millennium wheel on the South Bank in London last night, apparently snug in a bivouac tent slung beneath the apex of the massive structure.

Two international ecoprotesters were clinging to the top of the millennium wheel on the South Bank in London last night, apparently snug in a bivouac tent slung beneath the apex of the massive structure.

Two police climbers remained at the top of the wheel as darkness fell, but then came down. They had been dispatched to negotiate with the protesters but, after talking for more than half an hour, the demonstrators refused to budge from the 443ft-high London Eye. The police officers were understood to have given them a mobile phone so that communication could continue throughout the night.

The protesters climbed the wheel to proclaim their views on injustice and complain about dam-building projects in Spain and India. Starting before dawn, 10 people evaded security to scale the London Eye and unfurl banners demanding "Stop The Dams" and "Let the Rivers Run Free". Two groups climbed one-third of the way up on either side, while another group of experienced climbers went right to the top. This involved climbing upside down on the ladder that runs round the inside of the wheel, after which they established themselves in a red bivouac slung under the white metalwork.

Police used a combination of gentle persuasion and a helicopter to talk them down, and by late afternoon eight had been arrested on suspicion of causing criminal damage to the £35m wheel.

At one point the helicopter hovered next to the top group of climbers, while a police negotiator with a loud hailer shouted: "You've got lots of publicity, you've made your point. Come down, come down now!" The aircraft then circled the area before returning to display a copy of the Evening Standard newspaper. "You're right on the front page. Can you see it?" the negotiator shouted again. "Come down now, while it is still light."

Earlier, police had persuaded the lower groups to return to ground level. One of those from the top of the wheel also came down, because he was said to be "feeling unwell". But it was thought that two remained in place equipped with food, water and a hammock.

The action was led by members of Solidarios con Itoitz (SI), who have been involved in a long-running campaign against a dam project in the Itoitz valley in the Basque region of northern Spain. They were joined by two others, described as Anglo-Indians, opposed to another massive dam development in the Narmada Valley in central India.

One of these, calling himself Kuki, punched the air and shouted "Free Narmada" while being led to a police van after his arrest, but he added: "It was cold on the wheel and I was pleased to come down." His partner had been arrested while attempting to climb the structure at the beginning of the protest.

The incident poses serious questions about security at the wheel, which is due to open on New Year's Eve - riders will pay £7.45 for a possible view of seven counties. It is also an embarrassment for British Airways, the project's main sponsor, which has already endured adverse publicity over problems encountered erecting the wheel.

A spokeswoman for British Airways stressed that the company was responsible for security only after the wheel opened, but added: "An investigation is under way and, pending the outcome, we may review security procedures on the site."

Tim Renwick, project manager with the contractor Mace, which is constructing the wheel, said: "It's not high security. It isn't a nuclear base or an army camp. Short of having people with dogs and barbed wire there is nothing we can do."

Police Superintendent David George also confirmed that security would be urgently reviewed. "We will be talking to BA and holding a full review of what happened to make sure that a similar incident doesn't happen again."

Supporters of the protest said that the London Eye had been chosen to bring the dam projects to the attention of the whole of Europe.

"The wheel is a very emblematic monument," said Martin Errea, on behalf of SI. "It is a really good example of the waste of money in Western society while other people are being displaced and becoming homeless because of projects like these dams."

Eight members of the Spanish group are currently engaged in a European tour in an attempt to mobilise opposition to the Itoitz dam.

A leaflet distributed on behalf of the Narmada protesters claimed that dams being constructed there would leave more than a million people homeless. It concluded: "The people of the Narmada Valley have resolved to drown, rather than move from their land."

The height of fashion: Climbing stunts

Protesters seeking publicity regard high structures as attractive advertising points. Climbers are also drawn to them, but for different reasons.

Climbing techniques make such protests a safer proposition; at least one of the eight protesters on the millennium wheel yesterday was an experienced climber, said Nick Brown, who helped organise the protest. "They had had training from two climbers about what to do. They had harnesses and they were clipped into ropes all the time," he said.

One thing that rarely follows such an act is jail. Ascending tall structures (which climbers call "buildering") is not a criminal offence. Standard rope safety techniques are necessary, however, as most buildings offer fewer chances of protection than the Wheel.

Perhaps the riskiest is the 170ft Nelson's Column in London, where the only safe attachment for a rope is a rickety lightning conductor.

France's Alain Robert, an accomplished rock climber who scaled Canary Wharf tower in London in 1996, says he wants to climb the tallest buildings in all the main cities in the world, without a rope. Reacting to a similar urge, Britain's Leo Houlding, then 18, was on the way to a wedding when he passed the "Angel of the North" statue in Gateshead. The temptation was too much, and he scaled the 65ft statue in just 90 seconds.

Amateurs, however, are not recommended to copy him; he is probably one of the five best rock climbers in the country.