Ian James Terry, 32, was killed after suffering a gun shot wound to the chest while on the exercise.

The Independent Police Complaints Commission confirmed that Mr Terry, of Burnley, Lancashire, died after being struck by a single shot discharged from a shotgun carried by a colleague.

Police cars and an ambulance rushed to the scene and the officer was taken to North Manchester General Hospital but doctors could not save him and he was pronounced dead shortly after.

The "highly regarded" officer, who has not yet been named, was taking part in a pre-planned exercise involving firearms officers from Greater Manchester Police.

They were using a huge disused warehouse, known locally as the Sharp building, in Newton Heath, in the north of the city, to conduct the exercise.

It was the former distribution centre for Sharp, the electronics giant, which used to sponsor Manchester United. The site is heavily shielded by trees and a railway track and away from local housing.

The focus of the forensic investigation at the site appeared to be four cars parked two behind two and taped off from the rest of the goods yard at the warehouse.

One of the cars, a grey Citroen Xsara, appeared to have its front passenger window smashed, with glass on the ground below it. The driver's door was open as was the driver's door of the Suzuki Vitara car parked in front.

A Vauxhall Corsa was parked alongside the Suzuki and each of the two Citroen Xsara's parked directly behind them. A bulletproof jacket, oxygen mask, police helmets and a yellow jacket were on the ground close to the cars in the yard.