The ex-policeman, who uses the pseudonym 'Andrew Hanna', gave vital new evidence to this newspaper in an interview earlier this month.

Chief Supt Harry Breen and Supt Bob Buchanan . . .the most senior police officers to be killed in the Troubles . . . were shot dead in March 1989, near the village of Jonesborough, by a sixstrong IRA team. They were travelling home from a meeting in Dundalk garda station.

The Smithwick tribunal was set up by the government to investigate persistent allegations of garda collusion in the murder.

It had been commonly believed the RUC men had telephoned gardai to arrange the meeting in Dundalk only hours before their murder.

However, Hanna claimed the meeting was arranged three days earlier, allegedly giving the IRA ample time to plan the attack after a tip-off from a garda informer.

Hanna would likely have attended the meeting, only he was on holidays that week.

He said his two colleagues were sent to Dundalk to draw up a joint strategy with gardai to end the multi-million cross-Border smuggling empire of senior IRA commander, and later chief-ofstaff, Thomas 'Slab' Murphy.

Hanna said the IRA urgently needed Breen and Buchanan dead. Breen believed a garda in Dundalk was passing information to the IRA, and named that man to colleagues.