SINN Féin is "all take, with very little give in reply" when dealing with the past, Ulster Unionist Party leader Mike Nesbitt has claimed.
In a stinging attack, Mr Nesbitt said comments made by Martin McGuinness revealed the true nature of Sinn Féin's approach to legacy issues.
Mr Nesbitt accused the party of being "arrogant and outrageous".
In an interview with Sky News, Mr McGuinness said he would have no difficulty talking about his IRA past.
He said he was ready to answer any questions if new truth and justice structures were established in the north.
He insisted that the British government must open its files on the Troubles too, however.
"The mechanisms and structures that we have agreed be established make provision for families who have grievance and who are requiring a resolution to their grievance to go forward to these tribunals," Mr McGuinness said.
"If, in any circumstance, any of that has a connection with myself, in relation to people levelling allegations or whatever, then I will deal with that. That's not a difficulty for me whatsoever."
Mr Nesbitt criticised the comments.
"He knows as well as I do that the chief constable talks about the PSNI being in possession of some 10 million pieces of paper relating to the past, never mind what the army and security services hold," he said.
"He wants full and unfettered access to every scrap of paper, but in return all he is offering is the promise of having a chat about what he got up to.
"He has already made clear to the Saville Inquiry there are facts he will not disclose `under any circumstances' and this latest statement remains true to that sentiment.
"There is no balance in this approach. It is arrogant and outrageous in equal measure and therefore no basis for a deal on the past."
