The head of Taser International told a Canadian inquiry examining the police use of the stun guns that there was a big distinction between a Taser jolt being the cause of a death and being a contributing factor.

The inquiry was called after Polish immigrant Robert Dziekanski died after being hit with a police Taser at Vancouver International Airport last October.

The death brought international attention and intense criticism after video of the incident was released.

Taser International chief executive Tom Smith said Tasers were "generally safe" but did not rule out that death could result.

Asked if it could, Mr Smith said: "I would never say never."

Art Vertlieb, a lawyer for the inquiry, noted that statistics indicated more than 300 people - including about 20 in Canada - have had Taser use noted as a contributing factor in their deaths.

But Mr Smith said his understanding was that Taser had been cited only as a contributing factor about 30 times "as a potentially contributing cause".

"There is a difference between contributing and causing," he said. "There is a big distinction."

Mr Smith later told reporters he would not speculate on Mr Dziekanski's death and noted an official cause had not been released.

He used graphs and tables to show the inquiry that Taser use reduced injuries to officers and suspects and had "revolutionised law enforcement".