Taoiseach Micheál Martin has said there must be no amnesties for Troubles killings and the law must apply equally to everyone.
He was speaking after meeting families of those killed on Bloody Sunday at an event to commemorate the 50th anniversary of the killings.
Thirteen civilians were shot dead when British soldiers of the Parachute Regiment opened fire on people who had been attending a civil rights rally on 30 January 1972.
They were Patrick ‘Paddy’ Doherty, Gerald Donaghey, John ‘Jackie’ Duddy, Hugh Gilmour, Michael Kelly, Michael McDaid, Kevin McElhinney, Bernard ‘Barney’ McGuigan, Gerald McKinney, William ‘Willie’ McKinney, William Nash, James ‘Jim’ Wray and John Young.
A 14th person, John Johnston, who had been amongst the injured, died several months later.
His name is included on the official monument.
A further 15 people were injured.