The death of a soldier from 28 Engineer Regiment in Helmand Province was described as a "tragic incident" by the Prime Minster's spokesman today.
He said David Cameron's thoughts are "very much with the family and friends of the soldier".
The man, who hasn't been named, was shot dead by a suspected member of the Afghan National Army yesterday at Patrol Base Hazrat in the Nahr-e Saraj district of Helmand Province.
His family has been told.
He was the latest victim of a "green-on-blue" attack - where Afghans turn their weapons on their coalition colleagues.
The spokesman dismissed suggestions that a change of tactics are needed, insisting measures were already in place to improve vetting and screening of Afghan security personnel.
More top news
Feeling a little better tomorrow as less cold air sneaks in as we go into the bank holiday weekend.
The footage, taken from a dead Islamic State militant, shows the fighters in a chaotic and panicked battle with Peshmerga forces.
Solicitors acting for 20 of the families said they were "appalled to see the shambles in South Yorkshire Police" following the inquest.