Sinn Fein is not convinced the DUP is prepared to make a deal at intensive political talks, a senior party member has warned.
Leeds Castle in Kent is the venue for this week's talks
Northern Ireland's political parties are heading to Leeds Castle in Kent for talks beginning on Thursday.
Sinn Fein Chairman Mitchel McLaughlin
said the governments and the DUP needed "to face up to the challenges if we are to have a successful outcome".
Mr McLaughlin said his party was willing to enhance the Good Friday Agreement but would not accept the undermining of core principles.
"We are concerned that the governments may be tempted to make significant concessions to the DUP's anti-Agreement agenda and, in particular, their attempts to undermine the core principle of power-sharing and the all-Ireland architecture of the Agreement," he said.
The political institutions in Northern Ireland were suspended in October 2002 amid allegations of IRA intelligence gathering at the Northern Ireland Office.
This week's discussions, being chaired by the British and Irish prime ministers, are aimed at resolving issues surrounding the deadlock over the IRA's continued existence and power-sharing at Stormont.
Speaking in Belfast before travelling to England, Mr McLaughlin said the British and Irish Governments had not done the "hard work that was required".
Mr McLaughlin cited the failure of the governments to agree an independent judicial inquiry into the murder of Belfast solicitor Pat Finucane.
He said collusion was of crucial importance and Sinn Fein wanted a date for this inquiry as part of "acts of completion".
Mr McLaughlin said that if a complete deal was not reached at Leeds Castle, the governments should still address potential obstacles for future progress.
The DUP has insisted that any chance of agreement was dependent on the IRA taking "decisive and visible action".
DUP MP Jeffrey Donaldson said: "We are committed to delivering a fair deal for Northern Ireland and we have a mandate to achieve that fair deal.
"What we need now is for the IRA to move decisively and bring an end to the 35 years of violence and terrorism that has beset Northern Ireland and caused so much pain and suffering.
"Let's put that behind us, let's move on - the DUP won't be found wanting, the question is, will the IRA?"
Meanwhile, Ulster Unionist leader David Trimble said he hoped the talks would be the "last lap" in the political negotiations.
Mr Trimble said he was certain it was possible to reach a deal on restoring devolution, but it depended on others living up to their commitments.
David Trimble has hopes for the talks at Leeds Castle
He said republicans were "perfectly capable" of saying they were going to disarm completely.
"They are perfectly capable of saying: 'We are going to end all paramilitary activity and ensure that what exists are operating peacefully and democratically'," he said.
"I know no reason why they should not say that.
"They need to tell people why they have been stringing out the process for the last two years, why they have been frustrating the operation of the political process and we have to ask the government: 'Why have you been allowing them to do this?"
Mr Trimble said the main issues included paramilitarism, but also what the government intended to do about the situation.
He conceded that huge progress had been made in the last few years, adding: "I hope we are in the last lap.
"But it really depends on whether other parties and the government are prepared to face up to their responsibilities."
Meanwhile, senior SDLP negotiator Sean Farren said it was time for the two governments to "call the bluff" of the DUP and Sinn Fein.
Mr Farren said it was time to put the DUP to the test to see if they were willing to work on equal terms with nationalists.
He said that, at the same time, they must "call the bluff of Sinn Fein and the loyalists by testing them to see if they can deliver an end to paramilitarism".