"More and more we are seeing this hard-core factionalism driven frankly by people who are not Greens, but in some instances much more interested in unreconstructed political philosophies that have been discredited around the world," Mr Bowen said.

"The Greens are a political party obsessed with secrecy ... [Labor] have an open conference, everybody can come to see our debates. [The Greens] do it behind closed doors, have attempted coups and we find out about it six months later."

Fairfax Media reported on Thursday the increasingly open clash between moderate elements of the Greens, aligned with current and past leaders Richard Di Natale and Bob Brown, and those aligned with NSW Greens Senator Lee Rhiannon.

Senator Rhiannon described the party as being at a "crossroads" and said it should be more overtly challenging "ruling elites" as former presidential contender Bernie Sanders did in the United States.

Dr Brown has labelled Senator Rhiannon a "political white-anter" who is the "the Greens' version of [former prime minister] Tony Abbott".

"Bob Brown has called it out in relation to Lee Rhiannon" Mr Bowen said.

NSW Labor leader Luke Foley, who appeared alongside Mr Bowen at a Sydney press conference, described the Greens as being "at war with themselves. There is a civil war in the Greens while precious environmental protections are being unwound by a conservative government in Macquarie Street."

Mr Bowen said Labor had to engage in an "old fashioned debate about values" to push back against populism.

Senator Rhiannon has rejected Dr Brown's criticism of her, saying she was "collateral damage" in his dislike for the NSW Greens' candidates and processes.

"Bob always resented that NSW membership sometimes preselects candidates other than his preferred candidates, and also the fact that NSW did not support his preferred hierarchical model for the Greens' structure,"  she told ABC Radio.

The Greens' internal brawl has intensified since the recent formation of a new far-left faction within the NSW Greens called Left Renewal