Sinn Fein MP Martin McGuinness was today warned he faced accusations of having something to hide if he continued to refuse to answer questions.
Lord Saville, chairman of the Bloody Sunday Tribunal, adjourned the hearing temporarily to give Mr McGuinness an opportunity to consult his lawyers.
The chairman pointed out that he had refused to answer if he had been a member of the Official IRA, when he became Officer Commanding of the Provisionals in Derry and whether former Belfast councillor Sean Keenan had been explosives officer.
He added that Mr McGuinness had also not been prepared to state in which house he gave instructions to IRA members not to attack British troops on Bloody Sunday.
The chairman said he failed to understand why Mr McGuinness would not answer these questions when he had told the tribunal he wanted to get to the full truth of what happened.
"I would ask you to consider these questions. If you do not, two things will happen.
"Firstly you are depriving us of the opportunity of discovering the full facts and matters relating to Bloody Sunday, and secondly it will be suggested in due course that if you are not answering these questions you have something to hide."
After a short adjournment, Lord Saville assured Mr McGuinness's lawyer Richard Ferguson that the Sinn Fein leader's immunity to prosecution extended to the question of whether he had been a member of the Official IRA and when he became Officer Commanding the Derry Brigade.
Mr McGuinness then told the Inquiry that he had joined the Official IRA for a few weeks at the end of 1970 before leaving to join the Provisionals.
"At the time of Bloody Sunday I was adjutant in the Derry command of the IRA, within two weeks of Bloody Sunday, I became Officer in Command of the Provisional IRA," he added.
But Mr McGuinness continued to refuse to answer questions about the location of houses in which IRA members met or stored weapons.
"I have never, ever on any occasion given the name of a single person who was associated with me or the IRA. To do so would have been a gross act of betrayal.
"I do understand that we are in a different situation. I am not in an interrogation centre but I have a duty in my view, stretching back 30 years to these people and I am not prepared to break my word."
Lord Saville said he understood this to mean that his duty overrides the desire of the families to get to the truth of Bloody Sunday.Reuse content