An official in southwest China's Yunnan Province attended a "sex party" with at least three women, who took photos and video footage of the encounter with hidden cameras to blackmail him.

The photos and video clips involving Cheng, an official in Yunnan's capital Kunming, are authentic although some were altered somewhat with computer software, police said yesterday.

The three women in the photos and one other suspect have been caught and confessed to police, Kunming Daily reported.

Officers seized the video camera and a hard disc with the images and videos of Cheng in compromising positions, the report said.

According to police, the four used a dating website in April to invite Cheng over to a condo, where he had sex with three women at the same time.

They later allegedly blackmailed Cheng with the photos and video footage.

Cheng, who works with Kunming's development and reform committee, called police on July 31. He denied his role in the sex party and claimed the photos and video clips were fake.

On the same day, several pornographic photos of Cheng were uploaded to major online forums, drawing massive interest among Internet users.

Kunming police initially said a forensic test proved the photos were fake. They later said they were real.

Police said Cheng will likely face punishment for immoral behavior.