Amnesty wants tougher controls on the use of Taser stun guns.
Industry claims that Taser stun guns are safe do not stand up to scrutiny and tougher controls over their use are needed, says Amnesty International.
Taser guns - used by police forces around the world - deliver a 50,000 volt shock to disable suspects.
A report by the human rights group said Taser shocks caused or contributed to dozens of deaths in the US.
Amnesty urged governments to limit their deployment to life-threatening situations or suspend their use.
In its report on the use of Tasers in the US, Amnesty said between 2001 and August 2008, 334 Americans died after being subjected to a Taser shock, with medical examiners and coroners concluding that at least 50 of the deaths were caused or contributed to by the shocks.
'Open to abuse'
"The problem with Tasers is that they are inherently open to abuse, as they are easy to carry and easy to use and can inflict severe pain at the push of a button, without leaving substantial marks," said the report's author Angela Wright, a researcher at Amnesty International.
They can kill and should only be used as a last resort
Angela Wright Amnesty International
The study - which included information from 98 autopsies - found that 90% of those who died after being struck with a Taser were unarmed and many did not appear to pose a serious threat.
Many were subjected to repeated or prolonged shocks - far more than the five-second "standard" cycle.
Some people were even shocked for failing to comply with police commands after they had been incapacitated by a first shock.
In at least six of the cases where people died, Tasers were used on individuals suffering from medical conditions such as seizures - including a doctor who had crashed his car when he suffered an epileptic seizure.
He died after being repeatedly shocked at the side of the road when, dazed and confused, he failed to comply with an officer's commands.
Amnesty said US police officers also used Tasers on schoolchildren, pregnant women and even an elderly person with dementia.
"Tasers are not the 'non-lethal' weapons they are portrayed to be," said Angela Wright. "They can kill and should only be used as a last resort."
Tasers and other "conducted energy devices" are used in many countries, including Britain, Canada, France and the United States.
Archive footage of a student being tasered in Florida
The manufacturers and police forces who use them maintain that studies show they are a safer alternative to using firearms to control dangerous or combative people.
However, the human rights group claims these studies are limited in scope and have pointed to the need for more understanding of the effects of such devices on vulnerable people, including those under the influence of stimulant drugs or in poor health.
"We are very concerned that electro-shock weapons such as Tasers have been rolled out for general use before rigorous, independent testing of their effects." said Angela Wright.
Last Friday, prosecutors in Canada opted not to press charges against four police officers seen on video using a Taser gun on a Polish immigrant in Vancouver airport in October 2007. The 40-year-old man, Robert Dziekanski, died within minutes.
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