Police are investigating a possible sexual assault at Hugh Hefner's famous Playboy Mansion, officials said Wednesday.

The probe was launched Monday, according to a Los Angeles Police Department statement.

"For reasons of law and confidentiality that are critical in such investigations, no additional information will be released," LAPD spokesman Jason Lee said.

Rob Hilburger, a publicity director for Playboy Enterprises, said the company had not been contacted by authorities and did not know what prompted the investigation.

However, Hilburger noted there was a minor incident at Hefner's annual "Midsummer Night's Dream" party Saturday night involving a woman hired to work as a server and her ex-boyfriend.

The woman has a restraining order against the man, and she alerted Playboy's security personnel after the man tried to talk to her, Hilburger said. The man, who had been on the guest list, was then escorted off the property.

Hilburger said the mansion has a large security staff and there were no other incidents reported at the party, attended by 800 to 1,000 people.

"We obviously take this very seriously and we want to help anyway we can," Hilburger said of the investigation.

The mansion, located in ritzy Holmby Hills in West Los Angeles, is well known for hosting exclusive parties and events on its sprawling grounds.