DUP leader Peter Robinson joined party colleagues on Monday in attending all-party talks designed to break the deadlock over the status of the IRA and welfare reform.

Mr Robinson, who was admitted to hospital on Saturday following another health scare since his heart attack last May, attended the first of a series of roundtable talks at Stormont.

The DUP leader joined other senior politicians such as Gerry Adams and Martin McGuinness of Sinn Féin – and SDLP, Ulster Unionist and Alliance leaders, Dr Alasdair McDonnell, Mike Nesbitt and David Ford – in the talks hosted by Northern Secretary Theresa Villiers and Minister for Foreign Affairs Charlie Flanagan.

Mr Robinson attended the opening session of the talks, but then left Stormont House for other business close by at Parliament Buildings on the Stormont estate.

Mr Robinson (66), who suffered a heart attack in May, took ill on Saturday night and was admitted to the Royal Victoria Hospital in Belfast. A party spokesman said he suffered “a reaction to some medication and was admitted as a precautionary measure”.

He was released from hospital on Sunday night and joined the negotiations on Monday. Mr Robinson after the first session of talks said he had suffered a “bad reaction to some medication” which had been corrected and he was “feeling better already”.

He said parties must engage seriously right from the outset of talks. “They need to be taking the issues seriously from now. This party certainly is,” he said.

Mr Robinson said there had been some “grandstanding” at the first round of talks, but nonetheless there appeared “to be a level of realism about what needs to be done”.

Deputy First Minister Mr McGuinness said he took exception to some other politicians at Monday’s talks suggesting that Sinn Féin was linked to paramilitary criminal activity.

“During the course of this morning’s engagement I took these people to task. I told them that if anybody had any information whatsoever about any party in government involved in criminality they should put it up on the table. More importantly they should put it to the PSNI,” he said.

“In other words I told them it is about time to put up or shut up,” added Mr McGuinness.

“I am not going to be accused by others who are trying to besmirch the name of my party, particularly against the backdrop of the contribution (to peace and politics) that we have made,” he added.

“I am not putting up with this nonsense anymore,” said Mr McGuinness. “If people have information about a linkage between criminality and any political party in these institutions then they need to go to the PSNI, they need to put it up on the table at the talks, they need to produce the evidence and the intelligence that they have that such activities are taking place.”

‘Huge responsibility’

Before entering the talks, Mr McGuinness said his party was committed to resolving the outstanding issues. “There is a huge responsibility on all of the parties, and also on the two governments, to be creative and to apply a spirit of generosity in the course of these talks,” he said.

“The British government created the current budgetary crisis and must play a full and positive part in resolving this issue so that the Executive has a workable budget that will defend front line services and protect the most vulnerable in society.

“The Irish government too must act as a co-guarantor to the Good Friday and other agreements to support the full implementation of commitments made

made including its commitment on the A5 (road).”

The UUP leader Mr Nesbitt, after the first round of talks which lasted less than an hour, said the negotiations were “serious and focused”.

The current crisis was triggered by the murder last month of Belfast republican Kevin McGuigan who was killed in revenge for the murder in May of former Belfast IRA commander Gerard Jock Davison.

The PSNI chief constable George Hamilton in his assessment said the IRA still existed and that some of its members were involved in Mr McGuigan’s murder albeit without the sanction of the IRA leadership.

This prompted a series of unionist protest responses with the Ulster Unionist Party withdrawing its Minister from the Northern Executive. Subsequently Mr Robinson stood aside as First Minister and withdrew all his Ministers from the Executive apart from Arlene Foster who is holding the roles of acting First Minister and Minister of Finance.

Mr McGuinness said today that Sinn Féin had a “track record in opposing armed groups, violence and criminality that is second to none”.

Meanwhile, on Monday afternoon, DUP MLA Michele McIveen was temporarily appointed to the post of Minister of Regional Development.

This was the post held by Danny Kennedy of the UUP before he resigned as Minister following the police assessment of IRA involvement in murder of Belfast republican Kevin McGuigan.

Mr Robinson indicated that Ms McIlveen would take some “urgent decisions” before she would again resign in line with the current “not business as usual” strategy of the DUP.

'Sense of hope'

Shortly before the talks began, Northern Secretary Theresa Villiers again urged the parties to do a deal while acknowledging their opposing positions.

"I trust the leadership of the five main political parties in Northern Ireland that they want to make powersharing work," she said.

“So, with that in mind I approach these talks with a sense of hope but also realistically I know that positions on both sides of these issues are quite entrenched, and so it will be very difficult to get over them,” she told the BBC.

Ms Villiers, however, insisted there would be no extra cash from the British government for welfare.

“We have already provided through the Stormont House Agreement, an offer of an extra £2 billion in additional spending power,” she said.

“That is very substantial at a time of unprecedented pressure on public finances. We are prepared to negotiate, but not on extra money for welfare,” added Ms Villiers.

Resolving the key paramilitary and financial issues was “crucial”, she said. “You can’t have a functioning government without a workable budget and you can’t have a functioning government if relationships between partners have broken down completely over this paramilitary problem,” she said.

The talks are expected to last 4-6 weeks.

The three members of the new one-off commission which is to report on the status of the IRA and other paramilitaries and their involvement is criminality are to be named this week.

The commission, which was announced on Friday by Ms Villiers to facilitate the DUP angering the talks, is to report by mid-October.