Police on Monday called for any victims of abuse by Sir Ted Heath, or witnesses to any abuse, to come forward.

London's Mirror newspaper spoke to one alleged victim, now 64, who said he was assaulted at age 12 in an exclusive Mayfair flat in 1961 when Sir Edward was an MP. And the Guardian reported that detectives have spoken to a middle-aged man who says he was abused as a child by Heath several times.

Sir Edward died in 2005, aged 89. He was prime minister in the early 1970s and lost the leadership of the Conservative party to Margaret Thatcher in 1975.

Wiltshire Police were said to have heard allegations about Sir Ted Heath in the 1990s, but they were not followed up.

Superintendent Sean Memory told the BBC: "We had a senior retired police officer come forward (in late 2014) to inform us that they believed a trial may have been vacated [abandoned] as a result of information received in relation to Sir Ted Heath. We've looked extensively at that and we've decided to make a referral to the IPCC [Independent Police Complaints Commission]."

The IPCC inquiry will look at how the case was handled by Wiltshire Police and if the trial was stopped, why it was stopped, Supintendent Memory said. "More important for me today is, are there victims of sexual abuse from Sir Ted Heath or witnesses, and if so I would ask them to come forward today."

A dedicated team is waiting to hear calls. "I would actively encourage people to come forward. Trust us, we will treat any information we receive in strictest confidence."

An alleged victim told the Mirror that he had run away from home in the 1960s, was picked up by Sir Edward while hitch-hiking, driven to his "very posh" home, given a cup of tea and a sandwich and a bed for the night. He says that night the MP sexually abused him.

He said he reported the attack two months later but was "fobbed off" by social workers. Four years later he recognised his attacker's photo in a newspaper and told his mother of the attack. But he says he was branded a "liar and a fantasist". The newspaper said detectives had been told of the claims and planned to interview him.

Labour MP Tom Watson said he was given information on allegations of child abuse by Sir Edward in 2012. "A separate claim concerning Heath was made to me subsequently," 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."

In a statement the IPCC said it would investigate "allegations concerning Wiltshire Police's handling of an alleged claim of child sexual abuse made in the 1990s."

"It is alleged that a criminal prosecution was not pursued, when a person threatened to expose that Sir Edward Heath may have been involved in offences concerning children. In addition to this allegation, the IPCC will examine whether Wiltshire Police subsequently took any steps to investigate these claims. "

In a statement, Wiltshire Police said: "Sir Edward Heath has been named in relation to offences concerning children.

"He lived in Salisbury for many years and we would like to hear from anyone who has any relevant information that may assist us in our inquiries or anyone who believes they may have been a victim.

"Some people may never have spoken out about the abuse they have suffered but we would urge them to please contact us and to not suffer in silence."

The Sir Edward Heath Charitable Foundation, which operates the museum at Arundells, his home in Salisbury, told the BBC 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.

This year a national, independent inquiry into child sexual abuse will look at a range of scandals and allegations about abuse by the powerful, and within national institutions – including allegations against former MPs.

Its official aims are to "investigate whether public bodies and other non-state institutions have taken seriously their duty of care to protect children from sexual abuse in England and Wales.

"We will identify institutional failings where they are found to exist. We will demand accountability for past institutional failings. We will support victims and survivors to share their experience of sexual abuse. And we will make practical recommendations to ensure that children are given the care and protection they need."