The video was filmed secretly through an air duct
A videotape of a detainee being questioned at the US prison camp in Guantanamo Bay has been released for the first time.
It shows 16-year-old Omar Khadr being asked by Canadian officials in 2003 about events leading up to his capture by US forces, Canadian media have said.
The Canadian citizen is accused of throwing a grenade that killed a US soldier in Afghanistan in 2002.
He is seen in a distressed state and complaining about the medical care.
The footage was made public by Mr Khadr’s lawyers following a Supreme Court ruling in May that the Canadian authorities had to hand over key evidence against him to allow a full defence of the charges he is facing.
One of those lawyers, Dennis Edney, told the BBC his client was seen in a distressed state because he had been "abused" by his American guards.
"He was deprived of sleep by being removed from his cell and to another cell every three hours on a 24-hour basis for three weeks solid, followed by three weeks of deep solitary confinement," Mr Edney told the BBC.
Mr Khadr, the only Westerner still held at the jail, was 15 when he was captured by US forces during a gun battle at a suspected al-Qaeda camp in Afghanistan.
During the 10-minute video of his questioning in Guantanamo a year later, he can be seen crying, his face buried in his hands, and pulling at his hair. He can be heard repeatedly chanting: "Help me."
At one point he lifts his orange shirt to show the foreign ministry official and agents from the Canadian Security Intelligence Service (CSIS) wounds on his back and stomach which he says he sustained in Afghanistan.
"I’m not a doctor, but I think you’re getting good medical care," one of the officials responds.
Mr Khadr says: "No I’m not. You’re not here… I lost my eyes. I lost my feet. Everything!" in reference to how his vision and physical health were affected.
"No, you still have your eyes and your feet are still at the end of your legs, you know," a man says.
Sobbing uncontrollably, Mr Khadr tells the officials several times: "You don’t care about me."
In an accompanying classified document describing the interrogation, Mr Khadr also says he was tortured while being held at the US military detention centre at Bagram air base in Afghanistan, and that everything he had said previously was a "lie" because of the "torture".
The White House maintains that the US has treated all detainees held at Guantanamo in a humane way.
Mr Khadr was 15 when he was captured by US forces
The Bush administration argues that it needs flexibility and those it calls terrorists cannot be treated as if they are simply criminal defendants.
But one of Mr Khadr’s lawyers, Dennis Edney, said he hoped the video would cause an outcry in Canada and pressure Prime Minister Stephen Harper to demand that the US does not prosecute their client.
"I hope Canadians will be outraged to see the callous and disgraceful treatment of a Canadian youth," Mr Edney told the Toronto Star.
"Canadians should demand to know why they’ve been lied to."
Mr Harper reiterated last week that he would not interfere in Mr Khadr’s military tribunal, due to begin at Guantanamo on 8 October.
The human rights group Amnesty International described the video as "disturbing".
"We’ve always said that anyone suspected of involvement in international terrorism should be brought to justice, but what we see on this video is a travesty of justice," said Amnesty International UK’s Sara Mac Neice.
She added that the US should abandon its attempt to put Guantanamo prisoners in front of what she called "unfair military commission trials", instead allowing them "proper civilian trials in appropriate safe countries".
Mr Khadr, now 21, faces multiple terrorism-related charges, the most serious of which is murder. He faces up to life in prison if convicted.