Olympics-Rights group worried about Vancouver "sonic gun"

* LRAD can fire concentrated blast of sound

* Group fears may be used against protests at 2010 Games

* Police say LRAD to be used only as public address system

By Allan Dowd

VANCOUVER, British Columbia, Nov 10 (Reuters) - A Canadian civil liberties group accused police on Tuesday of quietly buying a high-tech audio weapon for possible use against protesters at next year's Winter Olympics in Vancouver.

The so-called long range acoustical device (LRAD) can fire a concentrated blast of sound powerful enough to cause hearing damage and temporary vision disruption, according to the British Columbia Civil Liberties Association.

The group, monitoring security for the 2010 Games, said there should have been independent safety testing of the "sonic gun" before Vancouver Police were allowed to buy it, executive director David Eby said.

The purchase, which was never publicly announced, "reduces the credibility of blandishments from city officials about not interfering with lawful and peaceful demonstrations," the civil liberties group said.

Vancouver Police bought the device last summer to communicate with large crowds and during natural disasters where audio systems such as hand-held megaphones are not effective, according to spokesman Constable Lindsey Houghton.

"To call it a 'sonic gun' is like us calling a 1972 Cadillac a 2,000-pound metal missile. It's a public address system," Houghton said.

Houghton said the equipment had already been used to address a large crowd of boaters during a fireworks event last summer, and the purchase had no link to the Winter Olympics, which will be held in the Pacific Coast city in February.

American Technology Corp (ATCO.O) says the LRAD, which it sells to military and police forces, can broadcast information from a safe distance and "creates increased standoff and safety zones" that help prevent the use of deadly force.

The company also says the equipment is not a weapon and that police have full control over the volume, which can be "easily and quickly adjusted based on situational use."

It can blast sounds of up to 152 decibels within one metre of the device and issue warnings over water to vessels up 3 km (2 miles) away. Sounds louder than a range of 120 to 140 decibels can cause pain and damage to human hearing.

Eby said it is "disingenuous" to say the LRAD is not a weapon, since that is how it has been used by police against protesters in countries including China.

Police in Canada have been criticized recently for increased and unnecessary use of Taser stun guns, amid safety concerns about the electronic weapons.