AN ARMS haul hidden on top of a hot boiler may have sparked a blaze that led to its discovery.
Two deadly AK47 assault rifles believed to have been used in separate attacks on police were among the cache found in the burning boiler house in the Rodney Drive area of the lower Falls Road in west Belfast on Wednesday.
Police last night said they believed the haul belonged to the dissident organisation known as the "New IRA".
The stash also included a high-powered rifle with a silencer, two sawn-off shotguns, three pipe bombs and 100 rounds of ammunition.
A 35-year-old man, who is believed to have been living in the house, was arrested under the Terrorism Act on Wednesday and subsequently released unconditionally.
Police last night said several rounds of ammunition exploded as firefighters tackled the blaze.
They believe one of the recovered AK47s was used to fire on officers in the Rosnareen Avenue area of west Belfast in November 2015.
During the attack up eight shots were fired at a parked PSNI car.
An experienced gunman is believed to have carried out the gun attack from a range of up to 100 metres.
Two officers in the car were uninjured but said to be badly shaken.
The second weapon may have been used to fire up to ten shots at a police officer on the forecourt of a garage on the Crumlin Road in north Belfast in January 2017.
One officer was shot in the arm three times during the attack.
Both attacks were claimed by the group styling itself the IRA.
The PSNI last night said they believe the recovered weapons belonged to that organisation.
Detective Superintendent John McVea said that a neighbour first reported the fire, with the occupant of the house also then calling the emergency services to alert them.
The PSNI man said that while it was still under investigation, one of the items may have sparked the blaze.
"It is no surprise to me that when you store pipe bombs and ammunition on top of a hot boiler, that is just a recipe for carnage, so that might well be the cause (of the fire), but that's still under investigation," he said.
The senior police officer would not be drawn on whether the weapons had been moved to the location ahead of a planned attack on police.
"The one thing I am pleased about is that these weapons are no longer in the hands of the terrorists and they have been put beyond use," he said.
"It's a significant haul of weapons in today's terms within terrorism and it is with pleasure that these weapons are no longer in the hands of these terrorists."
He said the organisation continued to pose a "severe threat".