Labour leaders and civil liberties advocates will be going to court next week to block the police from using controversial Long Range Acoustic Devices, also known as sound cannons, during the G20 Summit.

"This was a device that was not only designed to communicate, but also to disperse crowds by emitting painfully loud noises -- sounds that are loud enough to cause permanent hearing damage,' said Natalie Des Rosiers of the Canadian Civil Liberties Association at a Wednesday news conference.

"Our laws require that new laws be tested, that they be approved by the government before they are used on the general public."

A court will hear the application on June 23, two days before the G8 Summit in Huntsville. The G20 Summit in Toronto takes place on June 26 and 27.

Ontario Federation of Labour president Sid Ryan said he thinks the police have gone too far with security and will intimidate busloads of people who are coming to Toronto for a peaceful march on June 26.

"We're trying to put on here a family-friendly protest," he told reporters. "We want families to come out. We want them to bring their children out. We want them to bring their relatives out. No one should be afraid of marching with the labour movement, and yet we've got this armed force that's in our city, the likes of which I've never seen."

Last week, Toronto Police Chief Bill Blair said 3,500 of his officers will be working on summit security, supplemented by 1,600 more officers from out of town (another 2,000 Toronto officers are available to cover the rest of the city). He put the policing cost at $122 million.

He has said the LRADs will be only used as a communications device.

The unions and CCLA say that if that's the case, the police should agree to disable the sound cannon feature.

The RCMP will be in charge of the inner security zone that surrounds the Metro Toronto Convention Centre where the G20 leaders and delegations will actually be meeting.

JTF 2, the secretive special forces branch of the Canadian Forces, will reportedly be involved.

Police have rented a former movie studio on Eastern Avenue to handle any large volumes of arrested protesters.

Other developments

CTV News crews spotted a compound going up at the corner of Cherry and Commissioner Streets that appears to be something of an operations base for security forces.

More fencing went up Wednesday in the downtown core. A total of three kilometres will surround the inner security zone.

In another development that shows how seriously police are taking security, workers removed trees from the G20 summit security zone so that limbs are not used as weapons by protesters.

A selection of trees behind the security fence along Front Street near the Metro Convention Centre are being uprooted as a precaution, police said.

Every tree within the zone is being examined and removed if it is small enough to be moved by two or three people, Toronto Police Constable Wendy Drummond said.

The trees will be replaced following the summit, she said.

With a report from CTV Toronto's Alicia Markson