Austin Stack has interrupted a press conference held by Gerry Adams to accuse him of lying.

Mr Stack claims the Sinn Féin leader has information about who killed his father but will not reveal it to the guards.

The Portlaoise prison officer Brian Stack was fatally shot by the IRA in the 1980s.

Deputy Adams made a personal statement about the matter in the Dáil yesterday evening.

Interrupting a press conference at the Davenport Hotel in Dublin earlier, Austin Stack said: "Gerry Adams, you have information that is crucial to the investigation of my father's murder. Gerry Adams, you took myself and my brother Oliver in a blacked-out van to meet with a senior IRA figure - a man you say you trusted.

"Gerry Adams, I want you to give that information to An Garda Síochana. I am not interested in hearing any more of your lies and untruths [...] I want you to take the information that you have and bring it to An Garda Síochana, Gerry Adams, because you as a public representative are an absolute disgrace if you don't."

Deputy Adams 'rejected absolutely' any allegations that he had told lies or untruths.

"I'm quite content to co-operate with the guards on all of these matters," he added.