Thousands of soldiers are going absent without leave (Awol) because the Army cannot handle combat stress sufferers, the BBC's Panorama has reported.
Awol soldiers claim the Army ignores their problems
One soldier on the run told the programme he was ridiculed by the Army when he had problems after Iraq.
Mental health lecturer Steven Walker, who has interviewed ex-soldiers, said Army support services were stretched.
But the Ministry of Defence said fewer soldiers were going Awol, and most cases involved family issues.
And one former captain said the problem was sometimes that immature soldiers did not know how to face their problems and discuss them with their commanding officer.
There have been about 10,000 incidents of soldiers going Awol either temporarily or permanently since the invasion of Iraq, the MoD says.
It says there are now 2,300 incidents a year, compared with 2,700 in 2004.
An estimated 1,100 soldiers are currently on the run, some since 2001.
Mr Walker said not enough was being done for soldiers left traumatised by service in Iraq.
"The nature of the conflict is stressful - soldiers work inside civilian populations where they don't really know who the enemy is.
"The young soldiers I interviewed had traumatic experiences in Iraq and developed emotional and mental health problems that weren't acknowledged or dealt with properly, and that prompted them to go Awol," he said.
One soldier on the run tracked down by Panorama said he could not risk being sent back to Afghanistan or Iraq.
He said he sometimes felt he could not "handle the day" after his experiences in Iraq - but the Army authorities showed him no sympathies.
"They laughed about it - as they would do. I mean, a sick man is no good to them.
"Therefore they sort of ridiculed the fact that people do get down in the Army and do have problems."
Richie Livingston, from Glasgow, went Awol after a childhood friend and fellow soldier was killed in Iraq.
He tried a drugs overdose and was later found carving his mate's name into his own chest with a scalpel.
Richie says that despite this, an Army psychiatrist said he was fit to return to duty.
He then went Awol again.
"I felt they did not pay attention to what was going on and they thought I was basically putting it on," he said.
But not everyone is convinced that mental health issues drive soldiers to go Awol.
Amyas Godfrey, former captain and intelligence officer with two tours of duty in Iraq, had first hand experience of runaway soldiers.
"In my experience why the majority of soldiers went absent without leave was down to the fact that they were young, inexperienced and sometimes immature and they didn't know how to face their problems," he said.
"They didn't know they could go to their commander and say 'I'm really worried about my wife or the situation with my parents'.
"Usually they react badly and say 'it is all too much and I'm not going to come back'."
Speaking on behalf of the Ministry of Defence, Col John Donnelly rejected suggestions frontline trauma caused soldiers to desert.
"There's nothing we have that will suggest it is a particularly big issue," he said
Col Donnelly added: "We make great demands on our people, but we also put in place a very strong welfare network to support the soldiers who need to take advantage of it."