HONG KONG -- Hong Kong police arrested four more people in connection to a series of racy photos circulated on the Internet that appear to show several partially nude local celebrities.

Police arrested three men and one woman late Friday and early Saturday on suspicion of violating obscene material laws, police spokeswoman Josephine Cheng said.

She said the suspects, aged 29 to 31, have not been charged and were being detained for further investigation.

The scandal over the photos has dominated headlines in Hong Kong the past week. The pictures appear to show actor Edison Chen, singer Gillian Chung -- a member of the popular female duo Twins -- and actress Cecilia Cheung partially nude or in sexually suggestive poses.

Earlier this week, police arrested and charged a 29-year-old unemployed man with publishing obscene material related to the case.

The stars have not directly commented on the photos, but have issued statements either through lawyers or management companies condemning their release.

Chung's management company, Emperor Entertainment Group, said earlier the photos were doctored.

A hub for the Chinese-language movie and music industries, Hong Kong is known for its vibrant celebrity culture. Voyeurism in connection with local stars has stirred controversy in the past.

A magazine cover photo showing Chung changing after a concert in Malaysia sparked a major backlash in 2006.

A local magazine was shut down temporarily after it published a cover photo of a visibly distressed, seminude female, widely reported to be actress Carina Lau, in October 2002.