B.C. Premier Christy Clark's chief of staff, Ken Boessenkool, resigned abruptly Monday over an "incident of concern."

Clark said an incident involving Boessenkool occurred a few weeks ago but privacy laws prevented her from disclosing why he stepped down.

"This was a completely unexpected event. This is not the sort of thing that anyone can anticipate," said Clark, while answering questions from the media Monday morning. "I learned about it a couple of weeks ago and that is when the investigation began."

According to sources, the incident occurred Sept. 7, after many Liberal government politicians and staff members had participated at a golf tournament at the Metchosin Golf and Country Club just west of Victoria, to raise money for the B.C. Liberal party.

By tradition, media were also present and the event is considered off-the-record, to allow politicians and reporters to socialize freely.

However sometime afterwards, one source said Boessenkool and others moved the party to a Victoria pub a few blocks away from the Legislature.

Details of the incident are uncertain, but shortly thereafter the Premier's Office began an investigation of Boessenkool's conduct at the pub.

When the investigation was complete, the Premier met with Boessenkool. She said they both agreed he needed to resign, which he did.

Clark refused to comment on whether the incident involved a political staffer or whether Boessenkool was accused of groping a woman.

A former staffer for Prime Minister Stephen Harper, Boessenkool expressed regret in his resignation letter.

" . I acted inappropriately," he wrote. "I was wrong, regretted my behaviour very much and immediately and unconditionally apologized."

The Premier indicated the incident was not criminal in nature.

Clark replaced Boessenkool with Dan Doyle from BC Hydro's board. Doyle is a former VANOC executive vice president responsible for venue construction.