The Bloody Sunday Inquiry has directed Sinn Fein MP Martin McGuinness to name the officers of the IRA on Bloody Sunday.
Mr McGuinness was questioned by barristers
But Mr McGuinness said he would "rather die" than "betray" other IRA members by naming them at the Saville Inquiry.
He was speaking outside the Guildhall in Londonderry after the second day of his evidence to the inquiry.
The Bloody Sunday inquiry is examining the events of 30 January 1972 when 13 civilians were shot dead by soldiers during a civil rights march in Derry. Another man died later from his injuries.
Mr McGuinness told the tribunal on Tuesday that within two weeks of Bloody Sunday he was leading the IRA in Derry.
During two days of evidence, Mr McGuinness had refused to name other members of the IRA, saying his republican "code of honour" prevented him from doing so.
At the end of his evidence on Wednesday, tribunal chairman Lord Saville told him that in order to get to the truth of Bloody Sunday, the tribunal should be able to go to other IRA members and ask them for their evidence.
He directed Mr McGuinness to reveal the names, but Mr McGuinness again refused saying he would not "betray" other IRA members.
The Mid Ulster MP said he would repeat his call for anyone who had information about Bloody Sunday to come forward.
Lord Saville said he would have to consider what further steps he could take to get the names.
The BBC understands that one option may be to report Mr McGuinness to the High Court for being in contempt of the tribunal. That could result in a prison sentence.
Earlier, Edwin Glasgow QC, representing most of the soldiers who were in the
Bogside on Bloody Sunday, asked Mr McGuinness: "When did you leave the IRA, if you did?"
The Mid Ulster MP accused the inquiry of
being fixated by his past.
But he added: "I left the IRA in the early part of the
Mr McGuinness again refused to identify the location of an IRA safe house and an arms dump on Bloody Sunday.
Counsel to the Inquiry Christopher Clarke QC, asked him again whether he was prepared to identify a number of houses used by the IRA on Bloody Sunday.
The inquiry is examining the events of 30 January 1972
However, the Mid Ulster MP said he was not willing to betray the trust that people had placed in him and that he would never reveal their names.
He said he had on Tuesday night contacted people who
had provided assistance to the IRA but they had urged him not to reveal
"Family members would be put at grave risk of attack by loyalist
paramilitaries who have killed republicans and continue to target
republicans," he said.
Mr McGuinness was also questioned by barristers representing former IRA man Paddy Ward.
Mr Ward has previously claimed at the inquiry that Mr McGuinness was planning a nailbomb attack in Derry on Bloody Sunday.
However, Mr McGuinness said on Tuesday that Mr Ward was a "fantasist, liar and an informer who depended on and was being used by the British military establishment".
The Saville Inquiry opened in Derry three and a half years ago, but moved to Westminster's Methodist Hall to hear evidence from more than 200 former soldiers and some politicians.
Martin McGuinness pictured in the early 1970s
This session marks the beginning of the end of the evidence - the tribunal is hoping to hear all the witnesses by Christmas.
Lord Saville of Newdigate and the Commonwealth judges accompanying him on the inquiry are not expected to report back until next year.
The inquiry was established in 1998 by Prime Minister Tony Blair after a campaign by families of those killed and injured.
They felt that the Widgery Inquiry, held shortly after the shootings, did not find out the truth about what happened on Bloody Sunday.