Donegal superindendent Mr Kevin Lennon has been dismissed from the Garda.
The decision was made at yesterday's Cabinet meeting yesterday and announced officially today.
A brief Government statement said it had decided to dismiss Mr Lennon "pursuant to the powers vested in it by section 10(4) of the Police Forces Amalgamation Act 1925".
Supt Lennon and Det Garda Noel McMahon were found by the Morris Tribunal - investigating Garda activities in the Donegal division - to have orchestrated hoax explosives finds and to have offered the tribunal "a tissue of lies".
The Minister for Justice, Mr McDowell, resolved in July to seek the dismissal of Supt Lennon, who had been suspended from his job since August 2002.
Gardaí from the rank of superintendent and higher cannot be fired by the Garda Commissioner and must be removed from their posts by the Cabinet.
Supt Lennon will be the first senior officer to be fired in this way arising from the report of the Morris Tribunal. Det Garda McMahon has already resigned, while two other Garda officers have taken early retirement.
One of these, Chief Supt Denis Fitzpatrick, was said by the tribunal to have been "gravely at fault" for not properly investigating the activities of Supt Lennon, Det Garda McMahon and Ms Adrienne McGlinchey, who the men claimed was an IRA informer.
Mr Justice Morris found that Chief Supt Fitzpatrick was not involved in corruption, but should have followed up on the activities of this trio. His report also said that on one occasion Chief Supt Fitzpatrick had "abused his position to settle an old score" with Supt Lennon.