Northern Ireland's Democratic Unionist Party (DUP) leader has spent the night in hospital after suffering an adverse reaction to medication.
eter Robinson, 66, who suffered a heart attack in May, was admitted to Belfast's Royal Victoria Hospital on Saturday.
A DUP spokesman said he was doing well.
"Mr Robinson had a reaction to some medication and was admitted as a precautionary measure.
"He is doing well and will be discharged soon."
A spokesman for the RVH confirmed Mr Robinson had been admitted on Saturday night.
He said: "Peter Robinson was admitted to the Royal Victoria Hospital as a precautionary measure.
"He is comfortable and is doing well."
Mr Robinson, who has endured a punishing schedule in recent weeks, has temporarily stepped aside as First Minister following a political crisis sparked by the murder of former IRA man Kevin McGuigan last month.
His unexpected health problems come ahead of Monday's crunch talks aimed at saving the devolved Assembly at Stormont.
In May he spent four nights at the RVH after suffering a suspected heart attack and had three stents fitted to help the flow of blood.
At the time, Mr Robinson blamed his illness on an unhealthy lifestyle rather than the stress of his job.
Sinn Fein's Deputy First Minister Martin McGuinness has expressed concern.
He said on Twitter: "Concerned that Peter Robinson admitted to hospital but pleased that he is comfortable & doing well. Wishing him the best for recovery."
The powersharing Executive at Stormont is teetering on the verge of collapse after all but one of the unionist ministers pulled out.
The move followed a police assessment that Provisional IRA members were involved in the shooting of Mr McGuigan in a suspected revenge attack for the murder of former PIRA commander Gerard "Jock" Davison three months earlier.
On Friday Northern Ireland Secretary Theresa Villiers said an independent assessment of the structure and role of paramilitaries would be carried out enabling round-table discussions to resume on Monday.
On the agenda will be the full implementation of the Stormont House Agreement which aims to tackle legacy issues relating to Northern Ireland's Troubles, the budget and controversial welfare reforms.
Unionists had demanded UK Government action on paramilitaries before the talks could begin.
Mr Robinson said he was "content" key issues around paramilitary criminality had been addressed and confirmed his team would be at the negotiating table on Monday.