POLICE last night pledged to leave no stone unturned in the continuing hunt for Internet paedophiles after a string of arrests across the North-East.

Detectives used new technology to unmask people suspected of dealing in illegal images.

Simultaneous dawn raids were carried out at six properties in Stockton, Middlesbrough, Newcastle and Wallsend as part of a nationwide swoop.

Four North-East men, including a 15-year-old boy from South Bank, Middlesbrough, were questioned and then released on police bail.

Computer equipment and hundreds of CDs, believed to contain images of children being sexually abused, were also seized.

The crackdown, codenamed Operation Magenta, involved 34 police forces across the UK.

Among the 27 people arrested nationwide were teachers, care workers and people working in the medical profession.

Previously, sex offenders were able to hide on the Internet behind electronic aliases, but a breakthrough by programmers allows police to see instantly the name and address of anyone dealing in child pornography.

Detectives are delighted by the success of the "de-cloaking" programme and believe it marks a significant breakthrough in their bid to clean up the Internet.

The investigation was led by Hertfordshire Constabulary's Child Protection Unit and the Abusive Images Unit of Greater Manchester Police.

Cleveland Detective Constable Colin Robinson, who co-ordinated the operation locally, said: "There is no anonymity on the Internet for people who want to trade in shocking images of children. There is no hiding place."

Meg Colpitts, of North-East child abuse organisation Just Kidz, said: "I think it is brilliant that with new technology they have been able to arrest these people. But I think the problem of child abuse and pornography is getting worse, not better.

"It just shows what a sick world we live in."