'She told us that she noticed a digital camera was switched on during consultation at the clinic and the doctor was acting suspiciously,' the source said, but he did not reveal where the camera was placed.

Officers raided the doctor's home, also in Sha Tin, and found dozens of pictures, involving about 12 women patients.

The 29-year-old was arrested last Friday at the clinic in Tai Wai for possessing obscene articles for the purpose of publication. He is on police bail pending further investigations.

'The doctor is single and has worked in the clinic for about two to three years,' the police source said.

The Sha Tin regional crime squad is handling the case. Officers from the technology crime division of the Commercial Crime Bureau have investigated whether any pictures have been posted on the internet but have found nothing so far.

The doctor worked at the clinic as part of a medical group that has outlets across the city.

The clinic is now closed and has wooden boards placed around it with a note stating it is under renovation and advising patients to visit the group's other clinics.

The medical group employing the doctor did not respond to inquiries.

The Medical Council said it had acknowledged the case and would investigate if it involved professional misconduct. The council added that it would monitor events to determine its next move. A hearing might be conducted later to see if any disciplinary action would be taken against the doctor.

The case came less than two weeks after a similar incident.

On September 16, a 32-year-old primary school teacher was arrested for installing spy cameras in a classroom of the Church of Christ in China Heep Woh Primary School in Mong Kok, where pupils changed for dance classes.

A 10-minute tape was found showing about nine girls changing in the classroom. The teacher was sacked and police are investigating.