Retired Garda Corrigan strongly denies the allegations about his role -
Mr Corrigan told the tribunal that when Mr Donaldson made those remarks under parliamentary privilege, he was accompanied that day by Kevin Fulton, whom he described as "a reject from the British army" and "a fantasist".
Also there was campaigner Willie Frazer, whom Mr Corrigan said had "caused a riot when he came here with his Love Ulster parade".
The car in which Harry Breen and Bob Buchanan were murdered
Mr Corrigan gave a strong defence of his time in An Garda Siochana.
He said he had served the State loyally for 36 years and claimed he had "contributed more than any other member of An Garda Siochana to peace in our land".
Under questioning by legal counsel for the tribunal Justin Dillon, he said he took extended sick leave from the gardai in 1989 before retiring three years later because he had been ill-treated following a "change of regime" in the Dundalk station, when his "power base collapsed".
Mr Corrigan was being investigated for nine alleged breaches of discipline, including unauthorised use of official vehicles and being absent without leave from his duties on two occasions in July and August 1989.
On one of those occasions, RUC informer John McAnulty was abducted from a bar and murdered.
Mr Corrigan said he took "grave exception" to anyone questioning his loyalty.