LONDON, UK: Websites displaying child pornography fell by almost 10 per cent in 2008, but most of those images were still being peddled by commercial sites, an Internet watchdog said on Wednesday.

In its annual report, the UK-based Internet Watch Foundation (IWF) said 74 per cent of child abuse web addresses tracked worldwide were of a commercial nature.

Of those, three-quarters -- some 850 unique domain addresses -- were registered with just 10 domain-name registries, which manage and sell Internet addresses.

"These websites, although reducing in number, represent an extremely serious problem," said IWF Chief Executive Peter Robbins.

The police, hotlines and the internet industry had all helped to tackle the issue around the world, although the sophistication of some sites still poses problems, he added.

The watchdog advocated a series of steps to close the sites:

* Encourage public/private partnerships involving service providers working through a system of self-regulation.

* Remove online child abuse content quickly.

* Use filters to stop accidental access to sites.

* Promote partnerships with registries to delist domain names that circulate the images.

* Share more intelligence to counter cross-border crime.

The IWF said criminals used "incredibly high-tech" methods to take users to abuse sites and to cover their tracks.

Techniques included hopping between servers across continents -- using one, closing the operation down, and switching to another, an IWF spokeswoman said.

The number of sites containing indecent images of children had fallen nine per cent to 1,536 since 2007 and were down 21 since 2006, she added.

The IWF said 58 per cent of child abuse addresses contained graphic images involving penetration or torture, up from 47 per cent in 2007. Some 69 per cent of children appeared to be aged 10 or younger; 24 per cent aged six or under and 4 per cent aged two or under.

The Internet Watch Foundation is a charity, funded by the European Union and industry, that aims to remove child abuse, criminally obscene material and racist content from the Web.