The leader of the Progressive Unionist Party, David Ervine, remains in a critical condition at the Royal Victoria Hospital in Belfast.
It is understood he has suffered a heart attack.
The 53-year-old Assembly member and Belfast city councillor was first admitted to the Ulster Hospital in Dundonald, but was later moved to the Royal Victoria.
The Northern Secretary, Peter Hain, and Minister for Foreign Affairs, Dermot Ahern, are among those who have sent messages of support to Mr Ervine's family.
Mr Ervine was one of the key figures who helped broker the loyalist ceasefire in 1994.