A soldier from Salford, who has been deemed a suicide risk, says the government has sounded his "death knell" by deciding to extradite him to the US over fraud charges.
David McIntyre, 42, who served in Afghanistan, was given additional time by Home Secretary Theresa May to provide proof that he was suffering from an untreated post-traumatic stress disorder.
But despite providing further medical evidence, Mr McIntyre, who remains a reservist soldier, has been told he must be removed to the US.
Now living in Worsley, Mr McIntyre, 42, said: "I'm really disappointed by the decision. I can't put it into words. It's like a death knell."
His lawyer Karen Todner, of Kaim Todner solicitors, confirmed the Home Secretary's decision and said her firm was going to consider whether it could seek judicial review.
The Americans have accused Mr McIntyre, who served with the Queen's Lancashire Regiment and Royal Military Police, of overcharging a US peace group for a security contract when he was running his own firm - charges he denies.
Mr McIntyre, who faces a 20-year jail sentence if he is extradited to the US, served in the Territorial Army before joining the Queen's Lancashire Regiment in 1996.
He served in Bosnia and Northern Ireland.
He said he feared his removal could be imminent.
"I'm always the last to know, " he said.
"The Home Secretary could turn around and say 'He is going in two days'.
"That's really worrying me."
Mr McIntyre left the Army in 2002 and set up security company Quantum Risk, which employed a team of 20 to provide security to American clients, including the Iraqi ambassador to the US.
The business closed in 2009 and Mr McIntyre enrolled in the Royal Military Police, for whom he served in Afghanistan.
It was last July when the US charges emerged and the soldier was flown back from Camp Bastion, in Helmand Province, to face extradition proceedings.
Mr McIntyre faces eight counts of fraud concerning a contract with the United States Institute of Peace (USIP).
It is alleged he overcharged the organisation by 100,000 US dollars (#65,000).
He said: "There's no substance and I completely deny everything.
"I've never said I'm not prepared to stand in the dock - but to do it in the US, I know how they work."
Mr McIntyre said in the US he would be told to "cough to something he hasn't done" and sign a so-called plea bargain to ensure a short sentence or face never coming home.
"They're looking to give me 20 years," he said.
"The Home Secretary in all her wisdom has decided anything I've ever done for my country is completely defunct."
Mr McIntyre said he does not want to be treated differently because he is a soldier but added that he would like his "last 20 years in uniform to have counted for something".
He added: "I can't fight the US on my own."
His appeal was dismissed in February before he had presented the court with a report from the British Army's consultant psychiatrist confirming that he suffers from PTSD and warning that if he is extradited he could react "impulsively, dangerously and potentially tragically".
Mr McIntyre's legal team, which also represented Gary McKinnon, the so-called "hacker" whose extradition to the US was blocked by the Government, submitted further medical evidence to the Home Office - but to no avail.
The former soldier believes he is the victim of a plea bargain in which a US official, accused of similar offences, named him to secure a lenient sentence.
Mr McIntyre said he had been suffering from the severe anxiety disorder for many years but kept it private.
He said the extradition proceedings had worsened the condition and brought it to the fore.