NI First Minister Peter Robinson remains in hospital

Northern Ireland's first minister Peter Robinson remains in hospital after suffering a suspected heart attack.

Mr Robinson, 66, was taken to the Ulster Hospital, Dundonald, on Monday morning after he became ill.

The leader of the Democratic Unionist Party was then transferred to Belfast's Royal Victoria Hospital (RVH) where he underwent a procedure.

On Tuesday morning, his party colleague Arlene Foster said she understood his condition had stabilised.

The first minister's hospitalisation comes on the eve of a major debate at Stormont over welfare reform.

A statement from the hospital said: "Mr Robinson underwent a procedure this morning and is currently recovering in the RVH.

"He and his family have requested the need for privacy from this point onwards."

Mr Robinson has served as first minister and DUP leader since 2008, succeeding lan Paisley in both jobs.

The DUP has asked that the Robinson family's privacy should be respected.

Prime Minister David Cameron tweeted his best wishes to Mr Robinson, wishing him a speedy recovery.

Scottish First Minister Nicola Sturgeon also sent her best wishes.

Mr Robinson has served as first minister and DUP leader since 2008

DUP deputy leader Nigel Dodds said: "My understanding is that he took ill during the night and was taken to hospital.

"He is undergoing tests. It is very difficult to say at this stage what his current position is.

"Hopefully he will be back soon in his full job and will make a speedy recovery."

BBC Northern Ireland political editor Mark Devenport

Nobody could have planned for this.

However, talking to people within the DUP earlier today, the sense is that Mr Robinson's medical condition doesn't change what they said was a legally-driven deadline for the welfare reform bill.

It's all tied up with their hopes of getting a budget through Stormont.

It now looks like that welfare reform bill will be vetoed because both the nationalist parties have signed a petition of concern.

But at this stage, the intention is that the Social Development Minister, Mervyn Storey, is to still go ahead with that debate.

Meanwhile, one would assume another DUP minister might stand in for Mr Robinson as first minister.

That said, he may be out of hospital relatively soon, but in terms of going back to his desk job one would think that he would need to take some time out.

I don't think any kind of formal decision has been made, but we do know that there is a procedure within the Stormont rules that allows another minister to step in as acting first minister for a series of six weeks.

The DUP previously used that during the investigation into the Robinson family and him stepping down to clear his name.

Arlene Foster at that point stepped in so it's possible Mrs Foster could come in and do the same again.

Other politicians including Deputy First Minister Martin McGuinness, Sinn Féin President Gerry Adams, Ulster Unionist leader Mike Nesbitt, SDLP leader Alasdair McDonnell, TUV leader Jim Allister and Mr Robinson's Stormont colleague Peter Weir have wished Mr Robinson a speedy recovery.

Mr McGuinness tweeted that he was concerned to hear the news.

"My thoughts and prayers are with him, Iris and family," he said.

Mr Nesbitt said: "I am sorry to hear that the first minister has been taken into hospital this morning and I wish Peter a full and speedy recovery. Our thoughts are with him and his family."

The first minister's hospitalisation comes on the eve of a major debate at Stormont over welfare reform

Presbyterian Moderator Michael Barry sent "warm wishes" to the first minister and his family in what he said was "a worrying time" for them.

Controversial debate

On Tuesday, the Northern Ireland Assembly is due to debate the final stage of the controversial Welfare Reform Bill.

Speaking about the planned debate in light of the first minister's illness, Mr McGuinness said: "We will have to wait and see what happens overnight."

Last week, Mr Robinson warned that the assembly could not survive the scenario which would unfold if the welfare reform bill was not approved.

The Northern Ireland parties had agreed a deal on Westminster's welfare reform in the Stormont House Agreement last December.

However, Sinn Féin withdrew its support for the bill in March.

Sinn Féin and the SDLP have signed a petition of concern which means the bill appears certain to be blocked on Tuesday as it will not get the necessary cross-community support.