The case of an SAS sniper jailed for illegally possessing a gun is to be debated by MPs next week.
Sergeant Danny Nightingale, who served in Iraq and Afghanistan, was sentenced to 18 months in military detention by a court martial after pleading guilty to possession of a prohibited firearm and ammunition.
The case has sparked controversy, with supporters claiming the father-of-two, who has served for 17 years, including 11 with the SAS, has been betrayed.
Four special forces veterans, including the former commanding officer of the SAS, have written an open letter to David Cameron, claiming Sgt Nightingale was "the victim of a monstrous miscarriage of justice".
Today Julian Brazier, MP for Canterbury and Whitstable, who also sits on the Defence Select Committee, said he has secured an adjournment debate on Sgt Nightingale's case for Tuesday evening.
Mr Brazier, a former Captain in the SAS reserves, said: "I am deeply concerned about this case for two reasons.
"First this is no way to treat a man who has given so much for this country, and the sentence was especially harsh given the extreme extenuating circumstances.
"Second I believe that the unsatisfactory process in this hearing illustrates wider problems in the court martial system since it was shaken up in the 2006 Act."
Sgt Nightingale pleaded guilty to illegally possessing a 9mm Glock pistol which had been packed up and returned to him by colleagues after he had to leave Iraq in a hurry to help organise the funeral of two friends killed in action. He also admitted possessing ammunition.
Last week's court martial heard that the gun was a gift from Iraqi soldiers he had been helping to train, but the father-of-two, who had suffered medical problems affecting his memory, said he did not remember having it.
Today SAS veterans Lieutenant Colonel Richard Williams, Colonel Tim Collins, Andy McNab and Chris Ryan, wrote to the Prime Minister demanding immediate action.
In the open letter - published in The Sun - they called for Sgt Nightingale to be released on licence and the case reviewed.
Lt Col Williams, former commanding officer of 22 SAS and Sgt Nightingale's commanding officer in Iraq, and the other three men, said: "This shameful betrayal ruins 17 years of exemplary service - including 11 with the SAS.
"We say this prosecution should never have happened. Furthermore, we say he was bullied into a guilty plea. And lastly, we say the custodial sentence is completely disproportionate to the alleged crime.
"We say he is the victim of a shameful travesty of justice and we demand immediate action.
Sgt Nightingale's lawyer Simon McKay confirmed today that they are planning to appeal.
A Ministry of Defence (MoD) spokesman said: "We do not ordinarily comment on UK special forces for very good reasons.
"It would also be wrong to comment on the process, findings, convictions or sentences of a court that may be subject to appeal.
"It is for the courts, and the courts alone, to determine the guilt or otherwise of any person accused of an offence."