Police officers from 20 forces across the UK have taken part in a massive operation against child pornographers using the internet.

Homes in England, Scotland and Wales where people were suspected of viewing child pornography on the internet were raided at about 0700 GMT on Thursday.

The raids were the culmination of a six-month investigation carried out by Greater Manchester Police's Obscene Publications Unit.

In a "pro-active" operation detectives monitored the internet and traced people suspected of holding illegal images, said Inspector Terry Jones.

"It's basically going to a cold computer screen as we did do in April and May and again during the summer and looking at the activity, looking for intelligence, looking for evidence and supplying that to all these other forces."

Inspector Jones said the small initial number of arrests should not be taken as a poor result for the operation.

Links to abuse

"Recently, we arrested one individual and because we preserved and looked at the evidence on his machine, we were able to identify 49 others."

A priority would be to explore whether there were links between images on the equipment seized and the abuse of specific children, he added.

Arrests made following the raids included those of a 43-year-old man in Watford, Hertfordshire, an 18-year-old man from Abercarn, south Wales, a 33-year-old man in Pudsey, West Yorkshire and a 34-year-old man from County Durham.

In Scotland, Northern Constabulary said a computer had been seized in the Ross-shire area but no arrests had been made and no detentions had taken place.

The internet has revolutionised the pornography trade, with an estimated 20,000 new pictures posted every day. Fewer than 2% of these are thought to feature child pornography.

Law enforcers recognise that policing the internet for obscene material is becoming a growing problem, partly because the medium offers pornographers a cheaper, faster way to disseminate images than books or magazines.

Glitter disgrace

Disgraced pop star Gary Glitter recently got a four month jail sentence for downloading child pornography to his computer from the internet.

Last year, Operation Cathedral was launched across 15 countries to break the 'Wonderland' paedophile ring.

It resulted in Autumn 1998 in the largest ever seizure of paedophile material - including 750,000 pornographic images of children seized in the UK.

The UK's National Criminal Intelligence Unit has called for a dedicated national taskforce to be set up to target illegal internet pornography.

The internet industry is trying to regulate itself through the Internet Watch Foundation. The foundation regularly tips off police if it comes across material breaking the obscenity laws.

There are thought to be one million images of child pornography in circulation.

A conference two years ago was told that up to 27,000 people tap into paedophile pornography on the internet every day.

The forces which took part in the operation were Cleveland, Devon and Cornwall, Durham, Essex, Gloucestershire, Greater Manchester, Gwent, Hertfordshire, Kent, Lothian and Borders, Merseyside, Metropolitan Police, Norfolk, Northamptonshire, Northern, Northumbria, South Wales, Surrey, West Midlands and West Yorkshire.