The Democratic Unionist Party said today it will need a "prolonged period of assessment" to determine whether the IRA had given up its armed struggle.
But Sinn Féin leader Gerry Adams accused the DUP of engaging in "delaying tactics" and warned "the old days are finished and equality has to be the future".
Speaking after a meeting with British Prime Minister Tony Blair in London, DUP leader the Rev Ian Paisley said there could be no return to a power-sharing government in the North until his party was certain that the IRA had given up all its arms and ended its paramilitary activities.
Dr Ian Paisley shakes hands with Britain's Prime Minister Tony Blair as they
"We are not going to have any discussions about devolution until the requirements Mr Blair set out are fulfilled by the IRA," Dr Paisley said.
His deputy, Peter Robinson, added: "It will take a long period of time to make sure that they are gone and they are gone for good."
The DUP is furious about the pace of demilitarisation moves by the British army in the North, claiming they have been authorised before the IRA has even honoured its word to disarm and end its armed campaign.
They were also infuriated by the failure to consult unionist leaders over the proposed disbandment of the Northern Ireland-based battalions of the Royal Irish Regiment.
Widespread "normalisation" plans were announced shortly after the IRA's statement last Thursday that it was ending its armed struggle.
Dr Paisley accused the British government of having "caved in" to the IRA and given it "concession after concession" even though there was no proof that the organisation intended to give up its armed struggle.
Mr Blair was also today meeting a Sinn Féin delegation including Mr Adams and chief negotiator Martin McGuinness at Downing Street. Arriving for the talks, Mr Adams said that he expected they would take place in a "good atmosphere" following the IRA's announcement.
Mr Blair staged a brief photo call with the Sinn Féin leaders in the entrance to No 10 However there was no historic first public handshake with Mr Adams, despite speculation that it would take place.
Mr Adams sought to play down the issue saying: "I have shaken the prime minister's hand on a number of occasions."
In contrast however Dr Paisley was photographed shaking hands with Mr Blair when he arrived for his meeting in Downing Street earlier in the day.
Mr Adams issued a call to Dr Paisley to start talks on restoring power sharing. "I think he has a choice to make," he said. "Either he can join everyone else in building this process and let us get on or he can stand aside. I would prefer he would join us but that is his choice."
Mr Adams added that both governments needed to make clear to the DUP that they could not avoid a decision. "The governments cannot allow the DUP to delay and delay and delay again," he said.
Mr McGuinness said that he was convinced that the IRA would stand by its commitments and warned that it was important that the peace process should not be allowed to falter.
"If you wobble you are in big difficulty. We are not wobblers," he said.
"I think that the DUP need to regain their nerve. They need to recognise that they have a mighty contribution to make towards bringing peace to the island of Ireland and they have to play their part."
The Sinn Féin delegation also includes Assembly member Caitríona Ruane and Dublin MEP Mary Lou McDonald.
Additional reporting PA