Published Friday, 27 April 2012
But the deputy First Minister added that he has nothing to tell at Smithwick, because he has no knowledge of the incident.
The claims were made by former British army intelligence officer Ian Hurst, also known as Martin Ingram, at the tribunal in Dublin.
In a redacted version of his evidence the intelligence officer claimed the policemen's murders were "authorised at Northern Command and Mr McGuinness was involved as OC (Officer Commanding)".
The Sinn Féin MP labelled the claims a "yarn" and said Ingram, who claimed McGuinness was also involved in authorising "human bomb" attacks, was a fantasist.
Mr McGuinness made the comments on Friday at an international conference being held in Dublin which is examining conflict resolution in Northern Ireland.
The Smithwick Tribunal is investigating allegations of Garda collusion in the IRA murders of officers Breen and Buchanan, just north of the border in Co Armagh, 23 years ago.
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