A bishop is believed to be under investigation by officers from Operation Fernbridge – set up by the Metropolitan Police to look into historical cases of paedophilia.
The detectives are examining claims that the prelate protected priests who were sexually abusing youngsters, investigative website Exaro and the Sunday People can reveal today.
Officers are also thought to be probing other areas of the Catholic church that may have been involved in a large-scale cover-up of paedophilia.
The dramatic new move comes after the Jimmy Savile sex abuse scandal triggered massive Met investigations into allegations of offences by celebrities and politicians.
The Vatican has been rocked by major inquiries into claims of abuse in Ireland, the US, Belgium, Holland and Switzerland.
But this is the first time the Catholic church in the UK, which has its HQ at Westminster Cathedral, has faced such a probe – although there have been isolated cases at individual churches or schools.
A spokesman for the Church in England and Wales said: “I am not aware of any generic police investigation into sexual abuse linked to the Catholic church in the UK. Similarly, I am not aware of any investigation into a particular bishop. However, were there to be an investigation, clearly we would co-operate.”
Pope Francis called for “decisive action” on paedophile priests soon after his election last month.
His predecessor Pope Benedict was still a cardinal when he vowed in 2001 to tackle the “filth” of abuse in the church. But claims of a major cover-up persisted.
There has been a huge growth in police investigations into paedophilia since Savile was exposed as a serial abuser last October.
The scandal sparked Scotland Yard’s Operation Yewtree, which is investigating the late BBC presenter and DJ and other showbiz figures.
Operation Fernbridge is also looking into allegations boys in care in Richmond, south-west London, were sexually abused between 1977 and 1983 – initially at Grafton Close children’s home and then at Elm Guest House in nearby Barnes.
The first charges from this operation are expected within weeks.
The Met is also running Operation Fairbank to investigate alleged child abuse by senior political figures.
The Sunday People and Exaro revealed last week that Met commander Peter Spindler, who was overseeing the investigations, had made a surprise move to join HM Inspectorate of Constabulary, the official police watchdog.
An inquiry into 60 Catholic residential schools in Ireland found children were treated as prisoners and often raped and beaten.
In the US there have been hundreds of prosecutions of priests and others.