In a first for Asia, Hong Kong police said Thursday they will trial the use of video cameras attached to their uniforms to film exchanges with the public, despite concerns from human rights groups.

The southern Chinese city's police force said officers would start to wear the small cameras by the end of the year.

Similar devices have been deployed by police in the United Kingdom and United States, while police in the Australian state of Victoria are proceeding with a trial this month.

"We will try out the body camera scheme by end of this year," a Hong Kong police spokeswoman told AFP.

She played down criticism from human rights activists that the use of body cameras was a step toward the creation of a police state in the former British colony, which reverted to mainland rule in 1997.

"We are not targeting anyone at any public rallies but of course it could be a useful device for the police to deal with those who disturb public law and order at these rallies," she said.

The devices would be used by trained and clearly identified police officers, in order to enhance evidence gathering and public security, officials said.

But Hong Kong Human Rights Monitor director Law Yuk-kai said filming random interactions with the public could breach Hong Kongers' "constitutional right to privacy" and threaten the city's cherished freedoms.

He said there were no laws regulating the use of such cameras, fuelling fears that they would help security forces keep an eye on political activists opposed to mainland rule.

"It will create a climate of fear and turn the city into a police state with Big Brother watching us all the time," Law told AFP.

Pro-democracy activist Richard Tsoi said the threat of being filmed at protests would deter people from participating.

"People are afraid of being filmed... They don't know how the footage will be used and how it will be preserved," the vice-chair of the Hong Kong Alliance in Support of Patriotic Democratic Movements of China said.

The police want to buy about 7,000 of the British-made cameras, according to the South China Morning Post. The footage will not be kept for more than 30 days unless it is needed as evidence in court, the daily said.

Hong Kong is a semi-autonomous territory with a mini-constitution that guarantees civil liberties including free speech, a free press and the right to protest.

As such, the city of seven million people plays host to dissidents who could face arrest elsewhere in China, and is the scene of regular political rallies and pro-democracy protests.

Hundreds of thousands of people marched when Chinese President Hu Jintao visited Hong Kong on July 1 to mark the 15th anniversary of the handover, amid widespread fears that Beijing wants to roll back the territory's freedoms.

In Australia, Victoria Police Chief Commissioner Ken Lay said that in "difficult or dangerous situations" body cameras helped prove cases.

But he acknowledged that he had concerns about their use.

"I'm not that enamoured with the idea of police walking down the street and talking to their local members of the community wearing a camera. I don't think that's helpful to anyone," he told reporters last month.