The DUP missed a crucial opportunity to push republicans to act on their own promises, Ulster Unionist leader Mr David Trimble has said.
However, the UUP leader indicated it would still be possible to reach agreement on the restoration of devolved government before the end of November and that there were no problems that could not be resolved.
Speaking following a short meeting with the Taoiseach in Dublin this evening, Mr Trimble said the Reverend Ian Paisley's party lost a vital chance to get the result everyone wanted to see by failing to increase pressure on Sinn Fein six weeks ago.
"Coming out of Leeds Castle it was said by the Governments that, in effect, an offer had been made to them by republicans to deal with the issue of the private army and the weapons," Mr Trimble said.
"The DUP were naturally sceptical, but what they then should have done is put republicans to the test on this."
He said had they indicated a willingness to explore this offer, republicans could not have refused to directly disclose their proposals.
"I think the DUP made a mistake in not putting republicans under pressure," he added.
"In fact by drawing back and making it look like the DUP were reluctant to get engaged we have let republicans off the hook."
He said that was part of the reason why the deadlock surrounding the restoration of Northern Ireland institutions continued and was now "going round in circles".
The Ulster Unionist leader said a deal on restoring devolved government remained possible even if he still had doubts about the offer made by republicans on arms at Leeds Castle.
Mr Trimble claimed if the DUP had examined the offer they may have discovered it needed to be developed further.
He said it was still possible to reach agreement before the end of November and that there were no problems that could not be resolved.
Asked whether the Ulster Unionists were really determined to get the Northern Ireland Assembly up and running as quickly as possible, he said a large number did want to see devolution but others were content with direct rule.
"We have got to recognise there are different views within unionism on this issue," he said.
The Taoiseach has said November 26th is the deadline to restore the Northern Ireland Executive and Assembly - the anniversary of last year's elections.
PA