Image caption Sir Edward Heath was prime minister between 1970 and 1974

An inquiry into child sex abuse claims involving ex-Prime Minister Sir Edward Heath is exploring a "significant number" of lines, police say.

Wiltshire Police Chief Constable Mike Veale has defended Operation Conifer, insisting it is not a "fishing trip or witch-hunt".

He said officers had received "allegations spanning a significant number of individuals".

It emerged last month that two people had been arrested and bailed.

Former Conservative prime minister Sir Edward died at his home in Salisbury in July 2005, aged 89.

In an open letter, Mr Veale said he would not be "buckling under pressure to not investigate or to conclude the investigation prematurely".

He said he wanted to "set the record straight" amid press reports the inquiry was floundering.

'Satanic abuse'

The chief constable described Sir Edward as an "extremely prominent, influential and high profile person".

"The decision to undertake this incredibly complex and challenging investigation was not taken lightly particularly knowing, or at least expecting, that we would be placed under intense scrutiny," he said.

Mr Veale also confirmed reports that satanic ritual sex abuse was a feature of the investigation, although he said it was a small part and did not relate to Sir Edward.

Image caption Chief Constable Mike Veale said he would not "conclude the investigation prematurely"

He added that it was "important to ask the question, if the force had received allegations of non-recent child abuse against a former prime minister and done nothing, what would the reaction have been?

"Within the national context of the independent inquiry of exploring allegations of institutional failures in the past, Wiltshire Police was duty bound to record these allegations and launch an impartial and thorough investigation."

Operation Conifer began in 2015 after claims against Sir Edward were raised in an inquiry by the Independent Police Complaints Commission.

Information from a retired officer had sparked concerns that Wiltshire Police had deliberately caused a criminal prosecution against a suspected brothel keeper to fail in 1994.

Earlier this year the IPCC said it had found no evidence that the case was dropped because the woman threatened to make allegations against Sir Edward.

But Wiltshire Police has said Operation Conifer is also investigating a number of separate allegations made by persons who came forward. It said the inquiry additionally aims to safeguard children and vulnerable adults who may be at risk of abuse today.

The Sir Edward Heath Charitable Foundation has said it is confident the former prime minister will be cleared of any wrongdoing.