DUP Deputy Leader Nigel Dodds has called for those involved in the Bloody Friday atrocity 40 years ago to "come clean and admit their role".
Nine people were killed and over 100 injured when around 20 bombs exploded across Belfast on 21 July 1972.
Ten years ago, the IRA apologised to the civilian victims of its campaign of violence and offered its "sincere apologies" to the families of those killed on Bloody Friday.
Relatives of the dead and injured will mark the anniversary this weekend.
Mr Dodds said there has been a great deal of talk about reconciliation among some republicans and urged those with information to step forward.
He also called for an explanation as to why bombs were left outside railway stations, bus stations and shops.