The Palace Museum said on Monday that police are still investigating last month's nude photo shoot at the historic site, but that the museum still encourages artists to visit.

Palace Museum officials said in the statement that it told police immediately about the May 17 photo shoot, which included a nude female model in front of its ancient halls.

The museum also said it "welcomes artists from around the world to visit the Palace Museum and participate in a variety of artistic creation".

The four tourists involved in the shoot - the nude model and three photographers - avoided the usual Palace Museum crowds by arriving at their preplanned shooting sites early in the morning, soon after the museum opened. They were stopped by museum employees about 20 minutes later.

The photos later appeared online, triggering a passionate debate on social media over whether taking nude photos at the historic site was appropriate.

The museum said on June 1 that the photo work was "an act that violates social order and morality. ... It also severely damaged the cultural atmosphere that is associated with the Palace Museum".

The museum said two charges against the participants are possible under the Law of Tourism and Law on Public Security Administration Punishments, which would lead to a total of five to 10 days of detention.

"However, whether the shooting violated the law must be determined by the Public Security Department," the museum added.

Photographer Wang Dong, who headed the photo shoot, is studying for a degree in the United States after graduating from the Central Academy of Drama in Beijing. Wang said on his micro blog that he will cooperate fully with the investigation.

"I have made plans to avoid tourists and employees, I have no intention to show my work to the public, and I posted my photos only on my private photography platform, ... so I think I did not violate the Law on Public Security Administration Punishments," Wang said on his micro blog. "Besides, I need to clarify that the model didn't sit on the historic relics. She just posed" near them.

The Palace Museum, also known as the Forbidden City, is among the must-sees for tourists in the Chinese capital. Covering 1.12 square kilometers, it was home to 24 emperors in the Ming (1368-1644) and Qing (1644-1911) dynasties. It welcomed 15.27 million visitors last year.

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