The Metropolitan Police will investigate itself over allegations of corruption, including that it covered up child abuse involving MPs and police officers.
The Independent Police Complaints Commission will oversee the inquiry into what it called allegations of “high level corruption”.
The allegations relate to evidence dating from between 1970 and 2005. It includes claims that an abuse victim’s statement was altered to remove the name of a senior politician.
There is also an allegation of conspiracy within the Metropolitan Police to stop the prosecution of a politician suspected of abuse.
A former officer has claimed that police were told to scrap an undercover investigation that obtained evidence of abuse by late MP Cyril Smith.
Officers were allegedly told to hand over all their evidence and warned to keep quiet or face prosecution under the Official Secrets Act.
Cops allegedly failed to prosecute a senior Metropolitan Police officer who joined “members of the establishment including judges” in sexually abusing children.
One senior officer was said to have closed down an investigation, saying the order came from “up high”.
An investigation into suspected abuse at the Dolphin Square flats in Pimlico, south London, was allegedly dropped after officers got “too near prominent people”.