Individual members of the police and British army in Northern Ireland (search) may have aided car-bombers who killed 33 people in 1974, but there isn't proof of wider collusion, a long-awaited report into Ireland's bloodiest terror attack concluded Wednesday.

Nobody was ever charged in connection with the attacks, which went unclaimed for decades but were universally blamed on anti-Catholic extremists in Northern Ireland.

The mammoth report by Justice Henry Barron, presented to lawmakers and made public Wednesday after nearly four years of investigation, also harshly criticized the Irish government of the day, accusing it of demonstrating little interest or competence in bringing the bombers to justice.

On May 17, 1974, three car bombs went off within a few minutes of each other in crowded streets in downtown Dublin, killing 26 people, followed about 90 minutes later by a fourth car bomb that ravaged the border town of Monaghan, killing seven.

Barron said it was likely that individual police officers and members of the British army's overwhelmingly Protestant local regiment "either participated in or were aware of preparations for the bombings."

But the judge's report did not provide firm proof backing these suspicions. He cautioned that he had gathered no evidence of any high-level collusion between British security forces and the bombers.