A man who worked as an interpreter for the British army in Afghanistan has asked high court judges to watch a video showing six men being beheaded by the Taliban as part of a case against the UK government.

Mohammad Rafi Hottak says two of the victims, shown in the video being killed with a knife, were friends and former roommates who were targeted after they chose to work as interpreters with US forces.

Hottak, a father of three who fled to the UK in 2011, believes the video is evidence of the threat still facing former “locally engaged staff” employed by the Nato-led International Security Assistance Force (Isaf) in Afghanistan.

Hottak and a second Afghan who worked for the British army, referred to as AL, are seeking a judicial review of the government’s assistance scheme for foreign interpreters, arguing it unlawfully discriminates against them because they quit before the end of 2012.

In his statement to the three-day hearing in London, Hottak described the footage, saying a message in Pashto meaning “the consequences for the spies” runs across the screen throughout.

He wrote: “I cannot describe how I felt when I watched this video for the first time, even though some time has passed since my friends were killed. It broke my heart.

“I could not sleep properly and had awful nightmares. I fear for my life here in the UK and I feel terrified for my family back in Afghanistan. This video shows the extreme violence and brutality which interpreters face because of their work for foreign forces.”

Hottak was seriously injured by an explosion during a patrol with British soldiers in 2007 and worked recruiting interpreters in 2008 and 2009. He was twice attacked and also received Taliban death threats before being granted refugee status in the UK in 2013. AL remains in hiding in Afghanistan .

Lord Justice Burnett and Mr Justice Irwin were told by their barrister, Ben Jaffey, that both Hottak and AL had provided “loyal, important and dangerous service” for the UK armed forces.

But they and other interpreters like them were being discriminated against and treated less favourably than Iraqi interpreters whose lives became endangered working for the British during the Iraq war.

The two men, regarded by the Taliban as “infidel spies”, argue the scheme is unfair and unlawful because, with certain exceptions, assistance is not available to staff who left British employment before December 2012.

The Foreign Office and Ministry of Defence are fighting the claim, saying it is misconceived and that schemes have been put in place appropriate to “the circumstances in Afghanistan”.