A UK Government minister has warned Stormont's failure to implement welfare reforms will mean a £200m cut in Northern Ireland's annual Westminster grant by 2015.
He also warned that a £5m-a-month reduction will kick in from January. However, this will rise to £200m a year by 2015.
DUP and Sinn Fein remain at loggerheads over implementing the State benefits shake-up despite the looming deadline for finalising local legislation – and yet the stand-off has not been fully debated by Executive ministers.
With just over four weeks left in the current term – MLAs begin their three-week Christmas/New Year break on December 14 – there is insufficient time for the legislation to be amended and scrutinised further.
Social Development Minister Nelson McCausland would like to make public the details of discussions with Mr Penning's department at the end of June, but can only do so with the agreement of Sinn Fein.
Following a meeting with Mr Penning yesterday, the DUP minister argued the only significant changes were to regulations – which accompany the legislation and deal with how the reforms are implemented – rather than the legislation itself.
Accusing Sinn Fein of "dishonesty", he said: "For months I have been attempting to bring forward a Bill. Sinn Fein has blocked each attempt. In early September I shared a proposed draft Executive paper with Sinn Fein; as of yet I have not even had a response. Indeed, at last Thursday's Executive meeting I again raised this issue.
"I am publicly indicating that I am happy to release the document negotiated with the Sinn Fein leadership which they have not sought to amend following our discussions. I will release it as soon as (they) signal their agreement to publish it."
Mr Penning also pointed the finger at Sinn Fein, who he accused of "burying their heads in the sand". "The simple cost of welfare reform is, from January, a £5m deduction from the block grant which will rise through 2014 to £60m, and if you went through 2015 it would be in excess of £200m," he said
"What they can't expect to do is to call my bluff, and I think that is what they are attempting to do. I think it is one particular party that is attempting to do that and that is Sinn Fein."
Sinn Fein's Alex Maskey, chair of the DSD committee, said Mr McCausland was being "disengenous". "If he has a package, he should publish it. The fact is the discussions are not over and there is not a conclusive agreement, but if he wants to publish, let him go ahead," he said.
He told Mr Penning: "We will not be brow-beaten. Why should we be rushing headlong into something we know is a mess?
"The British Government has told us they want to bring in a Bill which will take £450m out of the pockets of vulnerable people. That is a dilemma we have to face up to. We have made it clear we are opposed to these Tory cuts."
Former SDLP minister Alex Attwood also said local parties should "dig deep, negotiate harder, (and) do not concede ground."
Ulster Unionist Michael Copeland, a member of the DSD committee, whose party also has amendments pending, said: "In Dublin, Sinn Fein is haranguing the Republic's government about "cuts", but here they are implementing cuts. Sinn Fein needs to agree on its message and then we can all get on with governing Northern Ireland."