Amnesty researchers claim stun guns are lethal

The weapons, designed to temporarily incapacitate by delivering a strong electrical pulse, are currently used only by trained firearms officers.

But Amnesty International described requests for all police officers in Scotland to be issued with Tasers as "a proposal we find alarming".

It called for a public inquiry into their safety and impact on policing.

The human rights body is holding a seminar on the devices at the Scottish Parliament in Edinburgh.

More than 150 Taser-related deaths have occurred in the USA and Canada since 2001, according to Amnesty.

Programme director for Scotland, Rosemary Burnett, said: "Our research in the USA shows that Tasers can kill.

"We hope that Amnesty's experience and research in America will help inform the debate in Scotland."

Green MSP Patrick Harvie said: "We have to question the notion that Tasers are non-lethal weapons.

"There is evidence that those with heart problems can be killed by a shock of this magnitude."

Norrie Flowers, chairman of the Scottish Police Federation, defended the use of the devices.

He insisted none of the deaths in the US had been directly attributed to the use of the weapon.

"We're talking about officer safety, we're talking about public safety," said Mr Flowers.

"Every single police officer is accountable for their actions, and no police officer takes it lightly when they have to use any kind of force."