The DUP had conceded too much to republicans in negotiations before the recent failed attempt to restore Stormont, Mr David Trimble claimed yesterday.
The Ulster Unionist leader accused the Rev Ian Paisley's party of conceding additional North-South bodies and of agreeing a position on the devolution of justice powers which went beyond anything agreed by the UUP last year.
He said that endorsement of Wednesday's British-Irish comprehensive agreement, published by Mr Tony Blair and the Taoiseach, Mr Ahern, meant that the DUP now supported the Belfast Agreement.
Holding a copy of the 1998 agreement in one hand and the governments' proposals published on Wednesday, Mr Trimble said that DUP support for the latter meant they accepted the other. "So, what were the last six years about?" he asked.
"What on earth were you doing for the last six years when at the end of the day you accept these?
"When you go through the detail of this you will see very little you have achieved for it all and lots of things you have done to meet the agenda of republicans."
He said that the latest proposals, backed by the governments and the DUP, mean that Dr Paisley would have to vote for a Sinn Féin Deputy First Minister and three Sinn Féin ministers. "Instead of voting for one, they will vote for four - I'm sure that's progress."
Mr Trimble claimed that Ulster Unionist efforts, which secured three acts of IRA decommissioning, and the decision "to blow the whistle" in October 2003 had brought republicans to their current position.
Voicing concerns about what he called side deals, Mr Trimble said he echoed calls by the Labour Party leader, Mr Pat Rabbitte, for the governments to detail what had been agreed on the release of Det Garda Jerry McCabe's killers and other issues not mentioned in Wednesday's paper.
Recognising that the proposed deal would have altered the Northern Ireland Act and the ministerial code, Mr Trimble said that "no changes were made to 30 pages of [ the] agreement. "Where is the Fair Deal?" he asked. "Where is the new agreement?"
After all the DUP's fuss on accountability of ministers, he claimed there was little substantive change. He accused the DUP of peddling a manifesto in last year's Assembly elections which was "a false set of goods".
That manifesto claimed that the DUP has campaigned against the Belfast Agreement and its form of devolved institutions.
Mr Trimble challenged Dr Paisley to detail publicly what changes to the agreement he believes he had made.
Last night, Mr Nigel Dodds countered, claiming that the DUP had injected accountability into the North/South framework through the Ministerial Code, Assembly scrutiny of implementation bodies and Assembly decision for issues outside departmental responsibilities.