Five police forces are investigating claims of historical child sexual abuse involving former PM Sir Edward Heath.
The Met, Wiltshire, Kent, Jersey and Hampshire forces are conducting separate inquiries into the late MP.
The BBC understands Wiltshire Police halted an inquiry into a brothel keeper in the 1990s after she said Sir Edward was involved in child sexual abuse.
The Sir Edward Heath Charitable Foundation said it was confident he would be cleared of any wrongdoing.
On Tuesday night, Hampshire became the fifth force to say it was investigating "allegations", but gave no further details.
The BBC's home affairs correspondent Dominic Casciani says claims made by the brothel keeper, Myra Ling Ling Forde, that Sir Edward was a client, meant that she had left herself open to prosecution.
However, the case against her was allegedly discontinued between 1990 and 1995.
She was later convicted of controlling prostitutes after a successful prosecution by Wiltshire Police.
She was jailed for six years after a trial that included allegations that she had supplied children as young as 13 to her clients.
It is unclear whether or not the force then went back to re-investigate her original allegations against Sir Edward - and this is now part of a corruption inquiry by the Independent Police Complaints Commission.
- Operation Midland: The BBC understands Sir Edward is being looked at as part of the operation examining claims that boys were abused by a group of powerful men 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.
- Operation Whistle: The States of Jersey Police has confirmed Sir Edward forms part of its investigation into historical allegations of abuse. It says some of the allegations relate to abuse "within institutions or by people of public prominence".
- Operation Hydrant: A nationally co-ordinated exercise to collate all allegations of historical abuse involving high profile-figures. The operation has been notified of Sir Edward being named in connection with an allegation of sexual assault in the 1960s.
The IPCC said on Monday that it would look at whether Wiltshire officers failed to pursue allegations of child abuse made against Sir Edward, who was Conservative prime minister from 1970 to 1974.
He died in 2005, aged 89, at his home in Salisbury.
A retired detective has alleged claims were made in the 1990s but not followed up.
Wiltshire Police has declined to comment, but has appealed for information regarding allegations against Sir Edward.
It and the NSPCC said they had received "a number of calls" from members of the public.
They said any lines of inquiry would be passed to the relevant police force and followed up.
Kent Police told the BBC it had received a report on Tuesday of a sexual assault having been committed in east Kent in the 1960s.
"The victim has named Sir Edward Heath in connection with the allegation. Detectives are making initial enquiries, and will obtain a full account from the victim. The report has been notified as part of Operation Hydrant," it said in a statement.
The Metropolitan Police Service (MPS) said it would neither confirm nor deny names of anyone who may or may not be part of its Operation Midland investigation.
A spokesman said: "Operation Midland continues to be a complex and sensitive investigation, and the MPS will not be giving a running commentary on its progress. This is important for the integrity of the investigation and protecting evidence that may form part of it."
Meanwhile, Labour MP Tom Watson said he had referred two allegations of child sexual abuse by Sir Edward to the police since 2012.
He said police had confirmed that at least one of those allegations was being investigated.
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 took Britain into what was then the European Economic Community during his time as PM.
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.
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