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 Australian police are also proceeding with a trial.

"We will try out the body camera scheme by end of this year," a 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.

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.