Northern Ireland's First Minister Peter Robinson has been admitted to the Royal Victoria Hospital in Belfast as a precautionary measure, a hospital spokesman has confirmed.
The 66-year-old Democratic Unionist Party (DUP) leader, who has endured a punishing schedule in recent weeks, was taken ill on Saturday and spent the night at the Royal.
A hospital spokesman said: "Peter Robinson was admitted to the Royal Victoria Hospital as a precautionary measure.
"He is comfortable and is doing well."
At this stage, the exact nature of Mr Robinson's illness is unclear.
In May he spent four nights at the RVH after suffering a suspected heart attack and had to have 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.