The Royal Marine jailed for killing an injured Taliban fighter in Afghanistan will be "released from prison on Friday", according to campaign group Justice For Marine A.

Alexander Blackman, 42, known as Marine A, had his conviction for murder quashed last month and his sentence changed from life in prison to seven years for manslaughter.

The appeal court accepted the grounds of diminished responsibility as he was suffering from a mental illness, known as adjustment disorder.

It was argued that during his tour of duty in Helmand during 2011 Sergeant Blackman and his men had been overstretched and under resourced.

He had lost close colleagues in Taliban attacks and was suffering from an undiagnosed adjustment disorder.

The former Sergeant has had many supporters campaigning for his release since he was sentenced to prison in 2013.

Mr Blackman's conviction came after video footage recorded on a camera mounted to the helmet of another Royal Marine, captured the moment he shot the insurgent.

At the time he said he believed the fighter was already dead and he was merely taking his anger out on a corpse.

He was "dismissed with disgrace" from the Royal Marines after serving for distinction for 15 years.