Sergeant Kevin Benderman cannot shake the images from his head.

There are bombed villages and desperate people. There are dogs eating corpses thrown into a mass grave. And most unremitting of all is the image of a young Iraqi girl, no more than eight or nine, her entire body except for one of her arms severely burned and blistered.Last January these memories became too much for this veteran of the war in Iraq. Informed that his unit was about to return, he told his commanders he wanted out and applied to be considered a conscientious objector. The Army refused and instead charged him with desertion. His case - which carries a penalty of up to seven years' imprisonment - has now started before a military judge at Fort Stewart in Georgia.

"If I have to go to prison because I don't want to kill anybody, so be it," said Sergeant Benderman.

The case of Benderman and that of others like him has focused attention on the thousands of US troops who have gone Awol (Absent Without Leave) since the start of President Bush's war on terror. The most recent Pentagon figures suggest that 5133 troops remain missing from duty. Of these, 2376 are sought by the Army, 1410 by the Navy, 1297 by the Marines and 50 by the Air Force. Some have been missing for decades.

But campaigners say the true figure of those who have gone Awol could be much, much higher. Staff who run a volunteer hotline to help desperate soldiers and new recruits looking to get out or else having discovered at basic training that military life is not for them, say the number of calls has increased by 50 per cent since 9/11. Last year alone, the GI Rights Hotline received more than 30,000 calls.

At the moment the hotline is receiving up to 3000 calls a month and the volunteers say that by the time a soldier or new recruit dials the help line he or she has almost always decided to get out by one means or another.

"People are calling us because there is a real problem," said Robert Dove, a Quaker who works in the Boston office of the American Friends Service Committee, one of several volunteer groups that have operated the hotline since 1995. "We do not profess to be lawyers or therapists but we do provide both types of support."

The people calling the hotline range from veterans such as Sergeant Benderman to new recruits such as Jeremiah Adler, an idealistic 18-year-old from Portland, Oregon, who signed to join the Army in the belief he could help change its culture. Within days of arriving for his basic training at Fort Benning, Georgia, he realised he had made a mistake and believed the Army wanted to do nothing more than turn him into a "ruthless, cold-blooded killer".

Mr Adler begged to be sent home to his family and even pretended to be gay in order to be discharged. Eventually he and another recruit fled in the night and then rang the hotline, which advised him to turn himself in to avoid court-martial. He will now receive an "other than honourable discharge".

Speaking from southern Germany where he is on holiday before starting college in the autumn, Mr Adler told The Independent: "It was obviously a horrible experience but now I'm glad I went through it. I was expecting to meet a whole lot of different types of people - some had noble reasons. I also met a lot of people who [wanted] to kill Arabs."