Speaking to a Senate committee examining the 2019-20 bushfires, the former fire commissioner defended his repeated attempts to meet with Prime Minister Scott Morrison last year about the risks climate change posed.

While Mr Mullins ultimately met with Emergency Management Minister David Littleproud and Emissions Reduction Minister Angus Taylor.

Liberal Senator James Paterson asked Mr Mullins what insights he would have provided that current fire chiefs could not.

"That's an interesting question. Probably none although some different perspectives I suppose," Mr Mullins said.

"One of the things I'll put to you is when I was commissioner I was constrained in talking about climate change because it was very inconvenient to some politicians.

"As a public servant I was required to stay within policy boundaries and not comment on policies and I had this drawn to my attention in no uncertain manner during one set of fires in particular.

"You'll hear current fire chiefs talking about drought, unprecedented weather conditions but they're very reluctant to get into the climate change debate."

Senator Paterson asked Mr Mullins whether he believed current fire chiefs were failing to provide "frank and fearless advice ... through the appropriate channels".

"I'm not saying that at all and I would never say that but I know from my own experience and other members of [Emergency Leaders for Climate Action] in a sense we self-censored because we knew what would be acceptable and what would not to certain political masters and if you went outside those bounds life could be made very unpleasant for you," Mr Mullins said.

Greens senator Janet Rice pushed Mr Mullins for details on the alleged retribution.

Mr Mullins said after he linked the 2009 Black Saturday fires to climate change in a Sydney Morning Herald article, he was given a dressing down by his minister and senior bureaucrats.

"I was spoken to by my minister at the time and senior officials saying not to buy into that, just don't, it's not your job, just fight the fires, it creates difficulties for us," Mr Mullins said.

He suggested current fire chiefs were under similar pressure, depending on which jurisdiction and under which political party they served.

Mr Mullins and other ex-fire chiefs were highly critical of the Morrison government's early handling of the bushfire crisis, and believed more houses could have been saved if their warning to lease more aerial firefighting units from the northern hemisphere were heeded.

Mr Mullins told the inquiry he believed key briefings from fire chiefs and the Bureau of Meteorology had not made it to Mr Littleproud and Mr Morrison until the fires were truly underway.