The soldiers were shot and killed at a checkpoint in the Nahr-e Saraj district of Helmand province.
Spokesman for Task Force Helmand, Major Laurence Roche, said: "I am saddened to report the deaths of two soldiers from 1st Battalion The Royal Gurkha Rifles who were shot and killed by a man wearing Afghan Police uniform at a checkpoint in the Nahr-e Saraj district of Helmand province.
"The loss of these soldiers is a huge blow to the Royal Gurkha Rifles and everyone serving in Task Force Helmand. Our thoughts are with their families, friends and fellow Gurkhas at this time."
Next of kin have been informed and have asked for a period of grace before further details are released.