The UK has the best track record in dealing with online child abuse, but there is no room for complacency, warned the Internet Watch Foundation (IWF).

Speaking at the IWF's tenth anniversary today, chief executive Peter Robbins said despite successes, the battle is far from won and the Foundation plans to raise its public profile further over the coming months.

The IWF, which monitors online child abuse websites, works with the internet industry, children's charities and police forces around the world. During the 10 years since it launched, it has successfully helped to bring down the number of child abuse sites hosted in the UK from 18 per cent to 0.2 per cent.

But Robbins warned evidence shows an increasing number of children are being abused and of particular concern is the growth in sites peddling hard-core abuse of children.

"We are seeing more images of different children being abused; not just the same images being re-circulated.

"The majority of images still tend to be pre-pubescent children and there is a worrying growth in sites hosting images of extreme abuse being set up," he said.

Although the IWF has been instrumental in bringing down more than 30,000 websites containing child abuse in the past 10 years, as most of the sites are hosted outside the UK, the biggest problem facing the IWF and the UK authorities is one of jurisdiction and the way this crime is handled.

The bulk of the world's child abuse websites are hosted in the US and Russia; with 51 per cent being traced to the US and 19 per cent to Russia. Robbins also cited Japan as "creeping up" up the IWF's radar over the past couple of years as paedophiles post on message boards telling people where they could find child abuse images online.

The IWF can't issue notices to internet service providers (ISPs) and other service providers in these countries to take down these sites.

Instead it is reliant on reporting to the relevant authorities in the countries where the sites are hosted and relying on their legal procedures.

For example ,Robbins said in the US they prefer to leave the sites live " while they carry out a sting". In the UK the site is taken down and evidence retrieved through computer records.

Having to rely on other countries' procedures has been less than successful in some cases. Robbins pointed out that for some years it has been monitoring 13 sites hosted abroad; one since 1995.

"Jurisdiction remains a significant problem," he said.

Jim Gamble, chief executive of the UK's Child Exploitation and Online Protection (CEOP) centre which now handles reporting of child abuse, agreed this was a stumbling block.

"In the past, law enforcement has been slow to get its act together," he admitted.

But he said things were getting better and the battle was slowly being won. He said a real step forward has been the setting up of the Virtual Global Taskforce.

This network of police forces from around the world work together to fight online child abuse. He said VGT police officers are currently talking to authorities in Russia. The hope is they will sign up to this network and tackle the sites hosted in that country.

Vernon Coaker, Home Office minister for policing, said other countries should take a leaf out of the way the UK tackles this crime. But he agreed awareness needs to be raised while without demonising the internet; instead people need to understand the issues and potential dangers.

"It is important that children are not discouraged from using the internet," he said.

The IWF therefore wants to raise its public profile. It said although it is now handling more reports from members of the public about suspect sites, with an average of over 1,000 reports a month, not enough people know about the organisation and online safety.

It is now embarking on an advertising campaign to raise awareness of how the public can help it tackle this crime as well as taking the conference to Birmingham, Manchester, Newcastle and Bristol.