One of the guns used in the gangland murders of two Dublin brothers two weeks ago was stolen from a PSNI officer, the Sunday Tribune has learned.

It is understood that a 9mm semi-automatic pistol that was found in the burnt-out wreckage of the getaway car that was used in the murder has been ballistically traced back to the PSNI.

Garda detectives are still liaising with their PSNI colleagues but it is understood that the weapon was stolen from an off-duty member of the force in the recent past.

It was one of 10 official firearms stolen from the PSNI/RUC since 1997. A spokesman for the PSNI declined to comment and directed all queries to the gardaí.

Garda sources say it is likely that the firearm was stolen from the PSNI member and sold to criminal gangs who in turn sold it to a west Dublin-based gang because it had no history of use in the south, which makes it extremely valuable.

It is understood that this is the first occasion where an official police firearm that has been stolen has been used in a murder and both gardaí and the PSNI are extremely concerned about the development.

Paul Corbally (35) and his 32-year-old brother Ken were shot dead on 28 June as they drove a Lexus on the Neilstown Road in Clondalkin.

More than 20 shots were pumped into the car and the two men died instantly. A 14-year-old boy who was sitting in the back of the car was injured and taken to hospital.

The PSNI gun was found in an Audi A6 that was found burnt out in Lucan just minutes after the double murder. The getaway car had been fitted with a false taxi plate so it would not draw attention from gardaí or members of the public.

The Corbally brothers were well known to gardaí as members of a west Dublin gang involved in drug dealing and armed robberies. They became involved in a dispute with a rival Ballyfermot gang which culminated in the murder of an English criminal outside a pub in Ballyfermot last September following a mass brawl. This led to a series of tit-for-tat incidents prior to the brothers' murders, including a murder attempt on the rival gang boss.