Those accessing the sites were white men working in IT.

The arrests were part of Operation Ore - a nationwide attempt to track down those involved in downloading images of children from the internet.

Thames Valley Police have revealed they are investigating the highest number of suspected cases of people accessing child porn outside London.

The investigation - called Operation Viola - which began in May 2002 has resulted in the arrest of 202 people and the seizure of 758 computers.

The figures released by police on Tuesday showed that all suspects were white and male.

It is worth repeating that every image involves the abuse of children and those accessing the images are playing a part in facilitating that Detective Inspector Bob Stirling

The force is now working with university experts to research the demographic of a typical offender and any link between people who access child pornography and those who go on to commit child abuse or other offences.

At a news conference at Thames Police Headquarters in Oxfordshire Detective Sergeant Bob Krykant said: "The majority of people seem to be people in computing and IT.

"But we have had a lot of changes in the area since 1999 - quite a lot of people didn't have access to a computer or the internet then."

'Sickened and shocked'

Officers have put the high number of offenders partly down to the large number of companies in the Valley's 'Hi-tech belt' with many having access to computers as home.

Detective Inspector Bob Stirling who led investigation said they had initially been "overwhelmed" by the number of offenders and sickened and shocked by many of the images.

"It is worth repeating that every image involves the abuse of children and those accessing the images are playing a part in facilitating that.

"I would say to anyone who is sitting at home, accessing this material on their computer, they should ask themselves why they are doing it - and to stop," said Mr Stirling.