NSW Labor's most senior official Jamie Clements has been hit with an apprehended violence order following an assault allegation from a former candidate for the NSW seat of Cronulla.

Stefanie Jones, who now works as a staffer for Campbelltown MP Greg Warren, contacted Opposition Leader Luke Foley's office with concerns following the alleged contact with Mr Clements, which is said to have occurred on or around budget day in June.

Both Ms Jones and Mr Clements, the general secretary of NSW Labor, have taken leave and neither could be reached for comment on Friday but it is understood Mr Clements denies the allegation.

A spokeswoman for Mr Foley told AAP that his office had taken steps to ensure the welfare of the staff member in question and that "she receives the appropriate support."

Mr Foley has also referred the matter to NSW Labor president and Unions NSW boss Mark Lennon.

Police told AAP they were 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 made at this time," they added.

The AVO application being lodged on behalf of Ms Jones is listed for mention in Sydney's Downing Centre Local Court next Wednesday.

Ms Jones' partner David Latham, a state organiser for NSW Labor, was not answering calls on Friday and did not respond to a request for comment.

Mr Warren, when contacted through a staff member, did not wish to comment except to say that he wished Ms Jones well.

On Friday, Mr Lennon issued a statement saying: "As the matter is subject to a police investigation it would, therefore, be inappropriate to comment further at this stage."