Police on Friday said five local men were arrested in relation to child pornography, as officers warned about AI-generated pornographic images.

Officers said five local men, aged between 16 and 49, were arrested last week on suspicion of producing and possessing child pornography, and obstructing a police officer in the execution of his duty.

They said hundreds of videos and photos related to child pornography were found in the suspects' electronic devices.

Police said pornographic images were found in a 16-year-old suspect's mobile phone, in which he was believed to have filmed his 11-year-old sister.

A police clinical psychologist, Fung Ho-kin, said that police, schools and parents need to work together more to prevent this from happening.

"They should, and they do, provide education to students as in what behaviour is acceptable on the internet and what is not," he said.

"I think they are doing workshops in some schools to teach their students how they should respond or how they should behave when they are faced with threats, including internet bullying or sexual exploitation."

Police said there were 80 cases in Hong Kong related to child pornography last year, and about 80 percent of the cases were in relation to online activities.

Officers said in a joint operation with authorities in Japan, Korea, Malaysia, Singapore and Thailand, a total of 435 people were arrested over the past two months.

They said some cases in other countries were found to involve AI-generated pornographic images, and officers warned that producing content involving child pornography electronically is also a crime.