The Met Police is investigating the late former Prime Minister Edward Heath as part of their inquiry into claims of historical child sex abuse by establishment figures, the BBC learns.
Sir Edward is one of a number of prominent names being looked at by detectives from Operation Midland.
Separately, the police watchdog is investigating whether Wiltshire Police failed to pursue claims in the 1990s.
The force issued an appeal for any potential victims to come forward.
Sir Edward died at his home in Salisbury in 2005 aged 89.
The development comes after the Independent Police Complaints Commission (IPCC) said it would look at whether Wiltshire officers failed to pursue allegations of child abuse made against the former prime minister.
A retired detective has alleged that claims were made in the 1990s but not followed up.
The IPCC will also look at whether a criminal prosecution was dropped when a person “threatened to expose that Sir Edward Heath may have been involved in offences concerning children”.
He said: “I passed them both to the police, who have confirmed to me that at least one of those allegations is being investigated and taken seriously.”
He said the different approach to allegations by different forces showed the need for a national police inquiry.
Operation Midland is examining claims that boys were abused by a group of powerful men from politics, the military and law enforcement agencies at locations across southern England and in London in the 1970s and 1980s.
It has focused on the Dolphin Square estate in Pimlico, south-west London.
Friends of Sir Edward have dismissed the claims saying there is not a shred of evidence to link him to abuse.
The Sir Edward Heath Charitable Foundation, which operates the museum at Arundells, his home in Salisbury, said it welcomed the investigation.
“We wholeheartedly believe [it] will clear Sir Edward’s name and we will co-operate fully with the police in their enquiries,” a spokesman said.
Sir Edward led the 1970-1974 Conservative government and took Britain into what was then the European Economic Community.
He lost his leadership of the party to Margaret Thatcher in 1975 – something he never forgave her for and he refused to serve in her cabinet.
He was also a successful author, a renowned classical musician and a world-class yachtsman.