British charities claim they are being targeted by internet pornographers who re-route their web visitors to sex sites.

Surfers trying to visit the British Heart Foundation and National Deaf Children's Society websites have found themselves suddenly connected to pages of sexual images.

The heart charity alleges it was the victim of "extortion" but there was nothing it could do.

The National Deaf Children's Society (NDCS) is locked in legal dispute with Nude Dames Chat Sex, a US porn website.

The two internet addresses are confusingly similar.

To all intents and purposes, it's extortion - the most frustrating thing about it is that there's nothing we can do

David Barker, British Heart Foundation

But it is no coincidence, according to a ruling by the international body in charge of domain names.

Web users who mistakenly visited the wrong site alerted the London-based charity to the problem.

Mark Raven, 38, from Chardstock, near Axminster, Devon, said: "I was horrified. The content is disgusting and it would have been all too easy for children to happen across it by accident."

The charity has challenged the US site's owner, Harold Meyer, and claims he wants $12,500 to surrender the name.

Susan Daniels, chief executive of NDCS, said: "This was totally unacceptable.

"He was unwilling to reconsider, so we had no choice but to take legal action to protect ourselves, deaf children, their families and other website users."

'Hijacking'

In April, the disputes resolution panel of the World Intellectual Property Organisation (WIPO) in Geneva decided Mr Meyer had deliberately bought the domain name with the intention of making money out of the charity.

Mr Meyer, of Wakefield, Rhode Island, was ordered to surrender it to the charity, but has yet to do so and has now launched a counter-claim in a US court - accusing the NDCS of stealing the name from him.

He said: "The National Deaf Children's Society tried to steal my domain, plain and simple.

"The new term for this behaviour is 'reverse domain name hijacking'. These charities are terrible - they act like the world owes them."

The panel also refers to a previous case involving Mr Meyer in which he was accused of trying to lure away visitors to the British Heart Foundation website, again with an almost identical domain name.

�20,000 demand

Although the BHF turned to the panel in Geneva, its complaint was rejected at the time, last November, on the grounds its initials were not sufficiently recognisable by the British public.

David Barker, of the British Heart Foundation, said: "Mr Meyer asked us for �20,000 for our domain name, then redirected us to the site of British American Tobacco when we refused. Then he re-routed it to a porn site.

"To all intents and purposes, it's extortion. The most frustrating thing about it is that there's nothing we can do."

Mr Meyer, 38, said: "They were kind of rude to us, so to get their attention, we temporarily directed traffic to the tobacco site and to the adult site."

Mr Meyer denied he was in the business of extortion.