One of the most powerful figures in the NSW ALP, general secretary Jamie Clements, has been hit with an apprehended violence order after a Labor staff member complained to police that he tried to kiss her in Parliament House during budget week in late June.

Stefanie Jones, 27, a staff member to Labor's Campbelltown MP Greg Warren, sought advice from Labor leader Luke Foley's office on Monday about the alleged incident and was referred to counselling and other services offered by the department of parliamentary services.

She later went to the police alleging that Mr Clements, 39, who is a married father of three, tried to kiss her in a room in Parliament House during the week of June 23.

In a statement, police said they "are conducting inquiries into the alleged assault of a woman within a room at Parliament House in June 2015".

"As the matter is the subject of a current investigation, no further comment can be provided."

Ms Jones is engaged to Labor state organiser David Latham. Mr Clements and Ms Jones were previously in a relationship.

A source close to Mr Clements said he "absolutely denied any wrongdoing and will be defending the allegations vigorously". The source said Mr Clements was "fully cooperating with police".

It is understood Ms Jones told police she felt concerned about returning to work, resulting in the police-initiated AVO.

The matter is listed for mention in the Downing Centre local court on August 12. Mr Clements has taken leave to fight the allegations.

Ms Jones was described as Labor's "secret weapon" when she featured in a recruitment video aimed at ALP supporters before the 2011 election at which she unsuccessfully stood for the seat of Cronulla.

A statement issued by Mr Foley's office confirmed that "a matter was raised with the Office of the Leader of the Opposition pertaining to an electoral officer of the NSW Parliament."

"The Office has liaised with the Department of Parliamentary Services to ensure the welfare of the staff member in question, and ensure she receives the appropriate support," it says.

"The Leader of the Opposition has also referred this matter to the President of the NSW Branch of the Labor Party. The matter is now subject to a police investigation, and as such it would be inappropriate to comment further."

As NSW Labor general secretary Mr Clements sits on the powerful administrative committee and also on Labor's national executive.

NSW Labor president Mark Lennon said in a statement: "The NSW General Secretary is currently on leave. As the matter is subject to a police investigation it would therefore be inappropriate to comment further at this stage."