The Agreement was signed in 1998
The British Government has been accused of damaging the Good Friday Agreement by focusing on extremist elements threatening the political process.
SDLP leader Mark Durkan made the comments in the run-up to key talks between
the political parties and British and Irish governments aimed at reviving the devolved
He said Downing Street had "pandered" to the more extreme parties at the expense
of the inclusive approach that had forged the original Agreement of April 1998.
"We found ourselves in a situation where political posturing and a tug of war
threatened the institutions and stalled the Agreement," he told the politics website, e-Politix, on Tuesday.
"The way the government managed that process was not the way we arrived at the Agreement."
Referring to earlier negotiations, Mr Durkan said the government had focused
on what he called "problem parties".
"That flawed approach has done damage to the Agreement. It hasn't just
interrupted the process it has corrupted it."
Mark Durkan said the government focused on "problem parties"
The political institutions in the province were suspended in October 2002 amid allegations of IRA intelligence gathering at the Northern Ireland Office.
Intensive negotiations involving the British and Irish Governments and the political parties are to take place in September in an attempt to restore devolution.
Mr Durkan urged the IRA to move into a "disarmament" phase and back words with action.
"Language in itself is not enough," he said. "What we need is decisive movement and the
IRA is in a position, and not before time, to make the moves they need for
"I want them to move from the ceasefire to a disarmament
Mr Durkan added that there also needed to be "positive and decisive movement" on
the part of unionist leaders.
Meanwhile, an Ulster Unionist delegation has held talks with Irish Foreign Minister Brian Cowen in Dublin.
The Ulster Unionists withdrew from the review of the Agreement saying the focus should be on ending paramilitarism, but they have now indicated they will take a full part in next month's talks.
After Tuesday's meeting, Sir Reg Empey, said the key issue was how seriously government was taking the Leeds Castle talks or whether they were "just another instalment in a long series of talks".
He said people were "bored, fed up and tired" of the current impasse because issues such as rates, water charges and jobs, were put on the back burner while "we are still trying to get people to move away from paramilitarism".
Sir Reg added that a move by republicans to "exclusively peaceful means" would bring about a "positive" response from unionism and loyalism.
Last Wednesday, Sir Reg said the Northern Ireland Assembly should be given "meaningful statutory functions", even if talks to restore power-sharing fail.