Defence sec Philip Hammond: 'Pain feels more raw'
17 September 2012 Last updated at 16:44 BST
The government has insisted that the safety of UK troops in Afghanistan is its "priority".
Two soldiers, Sergeant Gareth Thursby and Private Thomas Wroe, were shot dead by a rogue Afghan soldier on Saturday, who turned on them after faking injury.
Defence Secretary Philip Hammond told MPs the pain caused by such attacks was "more raw", as it undermined efforts to work with Afghan forces.