Published Tuesday, 24 April 2012
The claims were heard at the Smithwick Tribunal, which is investigating the shootings of Chief Superintendent Harry Breen and Superintendent Bob Buchanan on the Irish border in 1989.
Intelligence officer Ian Hurst - also known as Martin Ingram - said a "Mr McGuinness" was involved with the IRA's Northern Command as it sanctioned the attack.
A spokesman for Sinn Féin said Martin McGuinness "totally rejects these allegations", adding: "This individual who uses a variety of names including Martin Ingram has no credibility.
"By his own admission he is part of a British security apparatus which played a very negative and malign role in the conflict, including widespread involvement in collusion.
"His submission to the Tribunal needs to be seen and judged in that context."
Mr Hurst, who has been given permission by the Ministry of Defence to testify, gave the evidence during a private session last week.
A redacted version of Mr Hurst's evidence was read into the record by tribunal lawyers in Dublin on Tuesday and Wednesday.
He said: "It was authorised at Northern Command and Mr McGuinness was involved as OC (Officer Commanding)."
But the identity of the "Mr McGuinness" that the agent referred to has not yet been revealed in open session.
Ulster Unionist leader Mike Nesbitt has called on the deputy First Minister to give full disclosure of his knowledge of the murders of the high-ranking officers.
"During evidence given last week by Ian Hurst, which was made public today, it has been specifically alleged that the deputy First Minister, Martin McGuinness, was Officer Commanding of the Northern Command of the IRA and allegedly approved the murders of RUC Officers Harry Breen and Robert Buchanan," Mr Nesbitt said.
"This evidence raises a number of very serious questions which need to be answered today by the deputy First Minister. He owes it to the families of the murdered officers and the wider public to give full and honest disclosure of his knowledge of the murders."
Mr Hurst further claimed that the high-ranking double agent known as Stakeknife was Freddie Scappaticci and that he was also in the IRA's Northern Command and would have known about the RUC murders.
He added: "He (Stakeknife) was their most skilled investigator of suspected informers and he acted as one of their executioners."
The tribunal is investigating allegations of Garda collusion over the IRA murders of officers Breen and Buchanan just north of the border in Co Armagh.
They had been returning from a meeting with senior garda in Dundalk in the Republic of Ireland when they were attacked. The Provisional IRA claimed the murders.
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