An expert in explosives will be cross-examined later today on whether the bombs allegedly carried into Stormont by loyalist killer Michael Stone could have killed and seriously injured.

Michael Stone claims that he never intended to kill anyone and his incursion at Stormont was a piece of "performance art".

Dr Gerard Murray told a Crown lawyer yesterday that the devices Stone allegedly carried into the main entrance of parliament buildings at Stormont two years ago had the potential to cause serious injury, "horrific" burns and even death.

Stone claims the letter he sent to a Belfast newspaper saying he intended to murder Gerry Adams and Martin McGuinness and the incursions itself was performance art.

Dr Murray said had the nail bombs exploded they would have flung shrapnel "in various directions".

The flight bag, he said, which had contained a bundle of firework rockets taped to bottles of petrol containing chunks of fire lighters and a gas canister would have caused a "fireball".

He will be cross examined by the defence later today.