Police arrested a 29-year-old unemployed man yesterday who they suspect uploaded obscene photographs onto the internet, purportedly of local celebrities, over the past week.

The man was charged late last night with one count of publishing an obscene article and will appear in Tuen Mun Court today.

Earlier, the Commissioner of Police, Tang King-shing, said the internet was a black hole where enforcement of laws was difficult.

In response to reports of the nude "celebrity" photos, the Television and Entertainment Licensing Authority said it would discuss with internet service providers measures to limit the circulation of obscene articles on the internet.

Deputy Commissioner of Police (Operations) Peter Yam Tat-wing said the unemployed man was arrested in the New Territories and did not personally know the celebrities involved. Police were verifying the authenticity of photos on his computer, which would be sent to the Obscene Articles Tribunal for classification.

The photos that appeared on the internet purport to be of actor-singer Edison Chen Koon-hei, Gillian Chung Yan-tung of girl duo Twins    , actress Cecilia Cheung Pak-chi and former actress Bobo Chen.

Police did not rule out the possibility of more arrests.

"There are difficulties in tracing the source. Our technology forensics team is working on that but it takes time," Mr Yam said.

Police said they found the man through an internet service provider.

Internet Service Providers Association chairman York Mok said association members were approached individually by police with specific IP addresses of interest.

Mr Yam said two of the celebrities' management companies, which reported the obscene pictures to police, had been contacted for a meeting and police would contact the other celebrities involved.

Mr Tang said the most urgent task was to remove the pictures from the Web, and police were working with webmasters to achieve this. "Police have been patrolling the internet on a regular basis but enforcement of the internet is a black hole."

Tela said it had asked the association to remind its members to follow its code of practice by removing or blocking indecent or obscene articles. Further meetings with the association would be held to discuss additional measures to be taken.

Mr Mok believed most of the photographs had been removed from local websites but it was not possible to stop them from being widely circulated on mainland websites and even on a Hollywood gossip blog.

The graphic nude photos of a man and three women resembling the stars were found on internet discussion groups on Monday. More were uploaded during the week.

The management companies of Edison Chen and Chung reported the case to police earlier this week.