The IRA members who planted a bomb in Manchester are unlikely to ever face a trial, a former police chief has said.
The IRA bomb devastated a large section of the city centre
John Stalker, ex-deputy chief constable of Greater Manchester Police (GMP), made the claim in a BBC documentary.
IRA expert Prof Richard English told Inside Out lack of evidence and the sensitivity of the peace process may have prevented charges being brought.
Police said they were still investigating the 1996 blast, which caused an estimated £700m damage.
"The people of Greater Manchester can be reassured that we are continuing to review the case," a GMP spokesperson said.
But Mr Stalker, who was a senior GMP officer in the 1980s, told the BBC: "In my day, 10 years on, you would say 'This case is cold, it's dead, it ain't gonna happen', but these days, with DNA evidence and other things, these police are always reluctant to say a case is closed.
"But... I can't imagine any circumstances where anyone will be brought before the courts for this offence.
"They would have to do another one and be linked to the one 10 years before for that to happen."
The Manchester bomb destroyed a large area of the city centre, but a warning given by the terrorists allowed the area to be evacuated and fatalities avoided.
South Armagh Brigade
A massive police investigation was launched, but no charges were brought, despite officers asking the Crown Prosecution Service for permission to arrest a suspect.
Prof English, who has written a history of the Provisional IRA, said the bombing was carried out by the terrorists' South Armagh Brigade and the names of those involved were known to officers.
A lack of robust evidence was one possible reason why they had not been charged, but political pressures after the ceasefire of 1997 could also be responsible, he said.
"During the peace process period, the British government and the British authorities were keen above all that the IRA shift from something like war to something like peace," he added.
"There was a desire not to rock the boat. There was a sense that you could forget the past atrocities if the future was going to see Republicans be political, rather than being violent."
Inside Out will be shown on BBC One at 1930 GMT on 27 February.