A Brighton Royal Marine jailed for the murder of an injured Afghan insurgent is set to appeal his conviction.

Sergeant Alexander Blackman was jailed for life with a minimum term of 10 years after being found guilty of murder during a six-month tour of Afghanistan in 2011.

A court martial heard how 39-year-old Blackman shot the man in the chest with a 9mm pistol at close range shortly after he had been seriously injured in an attack by an Apache helicopter.

Yesterday the Judicial Office confirmed the married ex-commando, who is believed to have come from Brighton, had lodged applications for permission to appeal both his conviction and sentence.

The incident was caught on camera and showed the Afghan fighter struggling for breath on the floor.

Afterwards he turned to his comrades and said: ''Obviously this doesn't go anywhere fellas. I just broke the Geneva Convention.''

Blackman denied murder saying he believed the man was dead and he was taking his anger out on a corpse.

After his sentencing on December 6, Blackman said he was "devastated" at being handed a life sentence.

Known to friends and family as Al, the soldier said he was ''very sorry'' for his actions, which were filmed during a patrol in ''the most dangerous square mile in Afghanistan''.

He had completed tours of Iraq, Afghanistan and Northern Ireland during his 15-year military career and was being considered for promotion to Colour Sergeant before the murder video came to attention.

Yesterday a Government petition that demands the immediate release of Blackman had collected more than 58,000 signatures.

His wife Claire has previously praised the “outstanding” backing from the public, MPs and senior military figures.

Speaking on behalf of Mrs Blackman last month, solicitor Issy Hogg told a national newspaper: “She has been overwhelmed by the tremendous kindness and outstanding support which the British public has shown and would like to express her gratitude for the comfort this continues to provide.”