Peter Robinson has called on Gerry Adams to admit he was in the IRA.
The DUP leader hit back at republicans in the latest in a spate of tit-for-tat attacks.
He said his party's partners in government needed to come clean about their members' past. He also singled out Sinn Fein chairman Declan Kearney for special criticism.
"If Mr Kearney has the temerity to describe his speech as reconciliation then I suspect he would regard a knee capping as physiotherapy," he said.
Sinn Fein president Mr Adams has faced questions about his past.
Mr Robinson, speaking at a DUP Councillors' Association dinner in County Antrim last night, said: "If republicans genuinely want the truth to be told let Gerry Adams admit he was in the IRA.
"Let him disclose he was in its leadership.
"Let republicans confess responsibility for the Northern Bank robbery and let Sinn Fein leaders who have been named for involvement in terrorism by their former IRA colleagues come clean.
"Let the IRA give details of the multitude of murders and attacks they engaged in and then come and talk to us about setting up a truth commission."
Amid tensions between the largest parties at Stormont over delays to Executive decisions, the First Minister criticised a speech on Wednesday by Mr Kearney and said the party had lost the plot.
He accused republicans of "synthetic posing" while claiming to want a truth commission to investigate past atrocities.
"On Wednesday night at Westminster the mask strikingly slipped. Outreach was replaced by outburst," he said.
"Under the implausible cover of speaking about reconciliation Mr Kearney delivered a speech with all the venom and invective that was apparent at the height of the conflict.
"Perhaps 'reconciliation' is the Gaelic word for vitriol."
He said it defied understanding and stretched words beyond any natural meaning to describe Mr Kearney's contribution as anything approximating reconciliation.
"I appreciate that having fought a 40 year terrorist campaign the concept of reconciliation is somewhat new to the republican movement," he added.
"It was not often heard when they were engaged in murdering members of the security forces, ethnically cleansing Protestants along the border, terrorising their community, or conducting their criminal empire.
"But now that the notion of reconciliation has been revealed to them, they behave as if they are the first to discover it.
"They even claim to own the concept and believe everyone should join in their parody of it.
"Well they aren't, they don't and we won't."