Secretary of State Theresa Villiers has admitted she is not "hugely optimistic" the Stormont impasse over welfare reform can be resolved.

As it emerged she is remaining in the Northern Ireland job, she also bluntly warned Sinn Fein there is no more money to cushion the benefit changes.

An announcement from PM David Cameron confirmed Mrs Villiers, who has already told the political parties it is time to "get on" with implementing the Stormont House Agreement (SHA), is to stay in office.

On the welfare stand-off she confessed: "I am not hugely optimistic at the moment, it seemed during the general election campaign the parties are quite far apart."

But she added: "Now the election is out of the way I hope we can get down to reaching a solution."

The agreement has been in limbo since Sinn Fein pulled out of putting the legislation underpinning the massive changes through the Assembly.

And Deputy First Minister Martin McGuinness yesterday called on the five parties who reached the agreement to "work together" to combat the plans of the newly-elected Westminster Government.

He said the 18 MPs elected to Westminster last week - which includes four from his own party - would not "make a blind bit of difference" but the new Government would listen to a "united front" from the Stormont Executive.

Speaking at the first Assembly Question Time after the general election, Mr McGuinness said: "We need to be working together so that we can protect people as best we can." The senior Sinn Fein politician side-stepped criticism from Ulster Unionist Robin Swann that the £2m-a-week loss to Northern Ireland's block grant from failure to implement the benefit changes would be better going to voluntary and community groups.

Mr McGuinness said his party intended to stand firm to help changes affecting disabled children, severely disabled adults, the long-term sick and families with large numbers of children.

SF withdrew support from the Stormont House Agreement, hammered out between the five parties with the British and Irish governments in December, and the legislation required to kick-start the changes remains in limbo.

But the impasse could threaten the Governments pledge to make more loans available to finance the public sector 'exit' scheme, designed to shed up to 20,000 jobs, and commitments on corporation tax powers.

Mr McGuinness told MLAs, however, the SHA did not deal with the extra £12bn of welfare cuts announced by the Conservatives during the election campaign, as well as further cuts to frontline services, including health and education.

Alliance leader David Ford said completion of the agreement must be one of Mrs Villiers' main priorities.

"After Sinn Fein pulled their support for the welfare deal, which they still have not been able to explain, progress on these issues has been put on ice," he added.

"There will be serious consequences for the future of the public purse in Northern Ireland, and the institutions themselves, if we are not able to reach a deal on welfare and the budget."

Ulster Unionist leader Mike Nesbitt said he was fed up that the actions of parties who voice commitment to vulnerable people but hurt them instead. He revealed that Stormont meetings of the five main leaders had been "on ice" for weeks. And sole Ukip MLA David McNarry warned: "Northern Ireland is in for a shaky couple of years."

Belfast Telegraph