Matt Thompson says concerns about leadership and alleged incidents caused more than a third of the town's firefighters to quit last year, after a Professional Standards investigation failed to resolve the issues.

FRNSW has begun a new inquiry and Mr Thompson met with the agency's Executive Director People and Culture Michael Baldi last week to discuss complaints on behalf of five ex-firefighters.

These include an allegation of indecent assault, claims of incompetence, concerns over the station's leadership, alleged intimidation and imbalance between the way male and female firefighters were treated.

All five former firefighters confirmed with Australian Community Media that they left FRNSW because of the problems at the Dungog station. In one complaint, Mr Thompson's wife - firefighter Renae Thompson - alleged a FRNSW member indecently assaulted her at a Dungog pub. After the allegation surfaced, the station's female firefighters were told to change in and out of their uniforms in a small, cluttered shed outside while male firefighters continued to change clothes inside the station.

Mr Thompson said there was a dominant "boys' club" mentality in FRNSW. He said it was upsetting that, having put himself "on the line day and night for years on end", to then find that "standing up for basic rights and decent norms in the workplace" resulted in him leaving the service.

When asked for comment FRNSW said it "does not comment on employee-related matters".