The DUP and Sinn Fein have fiercely rounded on Secretary of State Theresa Villiers' threat to withhold economic aid if Stormont fails to make progress towards a 'shared future'.
The controlling parties in the Executive also argued the attempt to use the promised package – believed to include EU Peace cash – as leverage could backfire.
Finance Minister Sammy Wilson insisted it was the first time the Government had made the prospective funding conditional.
Mr Wilson also described Ms Villiers warning, revealed in the Belfast Telegraph yesterday, as vague.
And the DUP minister said she had also failed so far to get the Cabinet in London to deliver an economic package, particularly in relation to devolving corporation tax powers which has been put on hold until late next year.
The party's Lagan Valley MP Jeffrey Donaldson added: "The people who will suffer if the package is withheld are the very people we need to help if we are to build a shared future."
Former Sinn Fein junior minister Gerry Kelly said: "She might hold the purse strings and hold the money back but that is not going to work... she is being quite naive."
The party's Daithi McKay, chair of the Assembly finance committee, also added: "It is an absolute nonsense and distraction from the galling economic policies her Government has introduced including cuts to the financial package from the St Andrews talks."
Ulster Unionist leader Mike Nesbitt said the cash involved had to be considered in the context of the overall Block Grant to Northern Ireland, while the SDLP said both London and Dublin had promised to top up Peace 4 money.
But Alliance, which first withdrew from the Stormont group working on a revised Cohesion, Sharing and Integration (CSI) strategy, followed by the UUP, said Mrs Villiers' comments should come as no surprise.
The party's East Belfast MLA Chris Lyttle, who was a member of the group, said: "The reaction from DUP and Sinn Fein is one of embarrassment that this has now happened. We withdrew because the strategy that was being proposed was inadequate to the needs."
The package being negotiated with the coalition government includes funds from the Government's Infrastructure Guarantee Scheme – usually earmarked for projects of national importance – which could include schools, hospitals and roads.
Proposals also include the potential creation of enterprise zones, greater support for business start-ups and improving access to loans and Ms Villiers said they could potentially go beyond what has been offered to other parts of the UK. But she denied her remarks amounted to blackmail and said she remained optimistic that agreement would be reached.
However, she also added: "If we can't agree the package, yes, it is a fact that we may not be able to deliver some of the things we are talking about and discussing."
And while no figure was being put on the package, it was also being made clear it did not refer to the £153m offered to First Minister Peter Robinson and Deputy First Minister Martin McGuinness when they visited Downing Street last month.
Ms Villiers' comments came as she met community groups living on both sides of one of Belfast's peace walls, on the 15th anniversary of the Good Friday Agreement.
"We are talking here right next to one of the so-called peace walls which continue to scar the face of Northern Ireland," she said.
"I think we all agree, both the UK Government and the leadership of Northern Ireland's political parties, that progress is needed – this is a good opportunity to actually map out a pathway to that progress."