Hundreds of police officers have been accused of abusing their power to sexually exploit people, including vulnerable victims of crime, a damning report has revealed.
Watchdogs laid bare the scale of the issue they described as the most serious form of corruption - and rebuked forces over their efforts to root out cases.
Her Majesty's Inspectorate of Constabulary (HMIC) was asked by then home secretary Theresa May earlier this year to investigate the extent of the problem.
HMIC's initial findings identified more than 400 claims of abuse of authority for sexual gain over two years.
But HM Inspector Mike Cunningham said: "It is at least possible, probably likely, that the problem is more serious than the numbers that have been reported back to us.
"It's the most serious form of corruption. It is an exploitation of power where the guardian becomes an abuser. What can be worse than a guardian abusing the trust and confidence of an abused person? There can be no greater violation of public trust."
Home Secretary Amber Rudd said: "It is a matter of profound concern that any police officer should abuse their authority for sexual gain.
"The misconduct discovered in this report is shocking - it undermines justice and public confidence and there is no place in the police for anyone guilty of this sort of abuse."
Data collected by the watchdog identified 436 reported allegations of abuse of authority for sexual gain received by forces in England and Wales in the two years to the end of March. All but one constabulary had at least one case, while more than a third (39%) of the allegations involved victims of domestic abuse.
While forces acknowledge the seriousness of the problem, some are still failing to recognise it as a serious form of corruption, the report warned.
Less than half (48%) of the 436 reported allegations had been referred to the Independent Police Complaints Commission (IPCC). Figures also suggested there was an "apparent disconnect" between the numbers of alleged cases and sackings as a result.
In the wake of the report, IPCC chair Dame Anne Owers has written to all chief constables in England and Wales urging them to ensure all cases regarding abuse of authority for sexual gain are referred.