POLICE were called to investigate what may be one of the foulest strikes against one of the nation's richest families after an unknown person, erm, relieved himself on James Packer's Bondi doorstep on Monday morning.

A man in his early 20s stunned passers-by when he casually walked up to the luxury oceanfront property, pulled down his trousers and left a calling card at the entrance to the building - in broad daylight.

Inside at the time were the billionaire's wife Erica and their children Indigo, 21 months, and Jackson, three months.

The casino owner had just driven away from the exclusive address.

Yesterday it was not known if the perpetrator, who did his deed at 9.30am, was a disgruntled business associate, hysterical fan or an all-night reveller in urgent need of a toilet.

But the act of vandalism caused a huge stink at Packer family headquarters, with security alerted and the matter reported to police.

A security guard at the building confirmed he was aware of the incident and that it was all caught on CCTV.

"It was a shocking sight. It happened about 9.30am and anyone, including young children, could have been walking down that road," a stunned onlooker said.

"Everyone who walked past the place afterwards looked away in disgust. It was absolutely vile."

"If James saw it he would have been furious and his wife Erica will be sickened.

"It's not clear if this guy was targeting the Packers or if he was simply caught short.

"Whatever his reasons though, it was totally wrong."

"The scene was checked but no culprit was found," a police spokesman said.

Erica later left the property, walking within metres of the evidence, to get her hair done while the children remained inside with their nannies.