Rare footage of IRA members planning and carrying out a bomb attack on Queen’s University Belfast is to be broadcast in a BBC documentary.
Several people were hurt in the 1972 blast at the university’s sports hall on the Upper Malone Road.
The footage, from a lost American documentary, will be revealed in Tuesday’s episode of Spotlight on The Troubles: A Secret History.
The rediscovered film also shows weapons classes for IRA recruits.
In the programme, which covers the most violent period of the seventies, reporter Darragh MacIntyre also makes new revelations about the 1975 IRA ceasefire and the changes in the IRA leadership that followed.
Last week, the Troubles series showed previously unseen footage of Martin McGuinness carrying weapons and taking part in a car bomb attack in Londonderry in 1972.
The pictures were filmed for an American documentary called The Secret Army. It was based on a book by the same name written by New York academic J. Bowyer Bell.
The documentary was filmed in 1972, but disappeared after a few screenings in America.
The BBC Spotlight team tracked down some of the programme makers and made discoveries about the film’s disappearance, which will be revealed later in the series.
IRA members allowed a “secret army crew” to film a number of attacks that were carried out without masks.
The documentary also captured IRA attempts to shoot down helicopters in Derry, a Belfast IRA meeting led by Seamus Twomey, who later became the organisation’s Chief of Staff, and the funeral of member Colm Keenan.
The IRA killed more than 800 people during the period covered by this week’s episode (1972-78) in which the overall death toll climbed tenfold, from just over 200 dead to more than 2,000.
Episode Two of Spotlight on the Troubles: A Secret History will be shown Tuesday, 17 September at 21.00 BST on BBC One Northern Ireland and BBC Four.
Episode One can be viewed now on the BBC iPlayer.