'Unlawful society offences', which include being, or claiming to be, a triad member, have steadily declined in Hong Kong in recent years, police statistics show.

Chief Inspector Glenn O'Neill, of the Mong Kok crime division, said: 'The offence of being a member of a triad society is now harder to prove in court. Previously, if someone was overheard declaring to be a triad member, it was sufficient to go to court and prosecute him.

'Now, with increased civil liberties laws and awareness, the court demands a good deal more from the police to prove a case like this.'

Anyone who is, or claims to be, a member of a triad can face a fine of HK$100,000 and imprisonment of three years on a first offence, and a fine of HK$250,000 and imprisonment of seven years thereafter.

Police say last year there were 794 unlawful society offences, compared with 919 in 2001 and 824 in 2002, making up about 3 per cent of overall crime. In the first eight months of this year, there were 476 unlawful society offences, compared with 512 from January to August last year.

Chief Inspector Chung Tat-ming, also based in Mong Kok, heads a team of investigators who, in a two-year operation called Needle Sharp, have been closing down the sale and production by triads of illegal pornographic video discs.

'Technically, it's illegal to be a triad or to claim to be one, but most offences of claiming to be a triad member are attached to other criminal activities, like criminal intimidation or assault. These days, it is very rare for someone to be arrested just for claiming to be a triad member,' he said.

The Department of Justice denied there was a policy of not charging defendants for claiming to be triad members.

'There is no such policy in the Department of Justice. Whether to prosecute for claiming to be or being a member of a triad society, the offence will depend on the evidence in the case. We will also consider whether it is in the public interest to prosecute.'

Yau Tsim District, home to one-fifth of Hong Kong's licensed premises, attracts Wo Shing Wo and Sun Yee On triads, who act as bouncers, or extort money from owners and managers who refuse to hire their services, according to the district commander, Kevin Woods.

He said: 'It is very rare to actually charge someone with just being a member of a triad society because individuals know that it is not to their advantage to declare their membership. Mostly, triad offences are charged in connection with another crime.'

University of Hong Kong lecturer Chu Yiu-kong, an expert on triads, said the drop in unlawful society offences and arrests was related to the police's reluctance to charge individuals for simply being members of a triad society.

'There have been previous cases where prosecutors hesitated to charge somebody simply because they are a triad member. The judge may even turn it down. There has been criticism from the legal profession from a human rights point of view.'

According to the Organised Crime and Triad Bureau, the most active triad societies are the Wo Shing Wo, 14K, Sun Yee On, Wo Hop To and Wo On Lok, and they are mostly involved in illegal gambling, extortion, syndicated vice and debt collection.