Britain's police forces have arrested 660 suspected pedophiles after a six-month covert operation was launched to find people across the country who access indecent online images of children, Britain's National Crime Agency (NCA) said on Wednesday, adding that thanks to the operation, more than 400 children have been "safeguarded" from harm.

The operation, which involved 45 police forces across England, Wales, Scotland and Northern Ireland, led to the detention of doctors, teachers, scout leaders, care workers and former police officers, Reuters reported. Thirty-nine of the 660 people arrested were registered sex offenders, meaning that the vast majority of other unsupervised adults were not previously known to authorities.

In order to protect children and gather evidence against the accused, the operation was kept under wraps until Wednesday. However, the National Crime Agency refused to reveal tactics used to track down the suspects since it might help out in future missions. "This is the first time the UK has had the capability to coordinate a single targeted operation of this nature," NCA Deputy Director General Phil Gormley said in a statement.

Last October, efforts to better coordinate police action on issues such as child sex abuse and organized crime brought on the operation by the NCA, Britain's equivalent of the U.S. Federal Bureau of Investigation. "Some of the people who start by accessing indecent images online go on to abuse children directly. So the operation is not only about catching people who have already offended - it is about influencing potential offenders before they cross that line."

In recent years, Britain has been shaken by revelations that some of its best known celebrities from the 1970s and 1980s were involved in child sex abuse, according to Reuters. Children's TV entertainer Rolf Harris was sentenced this month to five years and nine months in prison for a string of indecent assaults against women and girls, while police revealed in 2012 that the late BBC presenter Jimmy Savile had been a prolific child abuser.

The publicity around those high-profile cases prompted a flood of accusations from people who say they were sexually abused as children. However, the NCA said the current operation was not aimed at historical crimes.

Although charges brought forward so far range from possessing indecent images of children to serious sexual assault, the NCA described the inquiries as ongoing, with not much detail available on how many suspects had been charged.

"The vast majority of forces around England and Wales are dealing with an unprecedented increase in the number of reports of sexual abuse of children," said Chief Constable Simon Bailey, the National Policing Lead for Child Protection and Abuse Investigations. "Forces are investigating exploitation of children and young people by groups and gangs, non-recent abuse including large scale investigations into abuse in institutions over many years and sexual abuse by parents and family members."