Media playback is unsupported on your device Media caption Fred Scappaticci has denied that he was an agent for the British Army

The army's most high ranking agent within the IRA is to be investigated about the murder of at least 24 people.

The army agent, who was given the codename Stakeknife, has been named by the BBC as west Belfast man Fred Scappaticci. He has denied he was an agent.

Northern Ireland's director of public prosecutions wants the new investigation to look at what information the army, MI5 and the Royal Ulster Constabulary's Special Branch received from Stakeknife.

Barra McGrory QC said those who received information he passed on will also be investigated.

The Police Service of Northern Ireland have yet to confirm who will conduct the investigation.

In a statement, Ass Ch Con Will Kerr said: "Police had received a referral from the director of public prosecutions which police were addressing. It would be inappropriate to comment further."

Who is Stakeknife?

Freddie Scappaticci is alleged to have been the most high ranking British agent within the Provisional IRA who was given the codename 'Stakeknife'.

He was the grandson of an Italian immigrant who came to Northern Ireland in search of work.

He has admitted, in the past, to being a republican but denies claims that he was an IRA informer.

He is believed to have led the IRA's internal security unit, known as 'the nutting squad,' which was responsible for identifying and interrogating suspected informers.

Mr Scappaticci left Northern Ireland when identified by the media as Stakeknife, in 2003.

Mr McGrory said: "I have been made aware of the scope and range of possible offences that may have been carried out by this individual and also members of intelligence agencies," he said.

Colossal

"This information has been provided to me by the office of the Police Ombudsman, Dr Michael Maguire, which is now concluding a painstaking review of all available material.

Image caption Barra McGrory QC held a press conference on Wednesday

"A common link across a significant number of potential crimes, including murder, was the alleged involvement of an agent of military intelligence codenamed 'Stakeknife'."

BBC NI Home Affairs Correspondent Vincent Kearney said the scale of the allegations against Stakeknife and his handlers are said to be colossal.

"Given that some of the allegations concern former members of RUC Special Branch, it is likely that Northern Ireland's chief constable will ask an outside police force to conduct the investigation," he said.

How is collusion defined?

Northern Ireland's Police Ombudsman is investigating the murders of alleged informers by the IRA - and Stakeknife's alleged role in them.

Image caption Mr Scappaticci left Northern Ireland when identified by the media as Stakeknife, in 2003

The director of public prosecutions said Dr Maguire had carried out a "comprehensive review" of material emanating from three investigations carried out by Lord Stevens.

Ex-Met Police commissioner Lord Stevens led three government investigations into security force collusion in Northern Ireland.

"A common link across a significant number of potential crimes, including murder, was the alleged involvement of an agent of military intelligence codenamed 'Stakeknife', Mr McGrory added.

Some of the families whose loved ones were allegedly killed by Stakeknife gave their reaction to the announcement.

They welcomed the news, but said they did not want the Police Service of Northern Ireland to lead any investigation and have called for an independent, international force to lead it.

The law firm KRW LAW, which represents some victims of the IRA's internal security unit, also welcomed Wednesday's development.

However, it said a statutory inquiry into collusion during the Troubles, including the activities of Stakeknife, was needed.