A Scout leader, a retired teacher and members of the armed services were among 76 people arrested in raids as part of an operation targeting suspected internet paedophiles.

Officers from more than 40 police forces executed more than 141 search warrants in the 48-hour operation led by the Child Exploitation and Online Protection Centre (Ceop).

Eighty children were "safeguarded" following the raids. One in four was found at the properties searched by police.

Most of the warrants related to image offences, including the possession and distribution of indecent images of children, Ceop said.

Among those arrested were a referee, a pathologist, government employees, a firefighter, an outdoor activities instructor and a computer programmer.

Known offenders who had breached the conditions of the sex offenders register were also arrested. More than 40 police forces were involved in the raids.

Ceop is publishing a report on Thursday on the risk posed by people who possess indecent images of children and recommendations about how police can protect children.

The specialist police child protection unit warns that anyone caught downloading child abuse images online poses a risk of committing physical sex attacks on children.

The images are becoming more extreme, sadistic and violent, but the severity and number of images held by offenders are not enough alone to assess the risk they pose or the sentence they should receive, the report says.

The warning comes after a watchdog claimed serious child abuse was rife across England, saying that girls as young as 11 "expect" to have to perform sex acts on rows of boys for up to two hours at a time in parts of London.

The deputy children's commissioner, Sue Berelowitz, told MPs her in-depth study of the problem suggested there "isn't a town, village or hamlet in which children are not being sexually exploited".

West Midlands police said they had raided six addresses over the past two days as part of the operation.

Three people were arrested and four children "safeguarded" after 35 officers executed warrants across the West Midlands force area in Wolverhampton, Birmingham, Solihull, Sandwell and Dudley.

The force said Operation Tharsley was a joint operation between 42 police forces and officers from the Serious Organised Crime Agency targeting people thought to be in possession of child abuse images.