The NSW Greens Supporters (No Nastiness) group was set up in early September by Jack Gough, a staff member of Greens MLC Jeremy Buckingham.

It follows ongoing hostility between Greens members on an existing group, including after the bitter contest to select a successor in the upper house to Greens MLC John Kaye, who died of cancer in May.

The contest came down to one between Justin Field – supported by Mr Buckingham – and candidates aligned with Dr Kaye and Senator Lee Rhiannon - sometimes referred to as the "eastern bloc".

The split in NSW is between members like Mr Buckingham, who think the Greens should aspire to government, and those who feel its best work is done as a minor party changing how politics is done.

Mr Field, the successful candidate, was reportedly labelled a "careerist leech" while his main backer Mr Buckingham and his allies on the right of the party were dubbed "tree Tories".

Tensions were exacerbated by Mr Buckingham's appearance on ABC TV calling for party reform in the wake of a disappointing federal election result in NSW, leading to calls for his expulsion.

Earlier, former Australian Greens leader Bob Brown had called on Senator Rhiannon to resign in the interests of renewal.

In a post explaining the new Facebook group, Mr Gough described it as group for "NSW Greens members to share information, discuss campaigning and debate ideas".

"Different perspectives are welcome and respected and this includes questioning Greens policy, processes or directions," he wrote.

"Robust debate is welcome. Non-conformity is welcome. Nastiness is not."

He added: "If you are nasty in this group you will be removed. People who have demonstrated nastiness on other Greens online forums will not be added. If you don't like this, tough – there are many other forums to discuss the Greens."

However, one Greens member told Fairfax Media: "The people who've not been allowed to join are people who have directly criticised Jeremy Buckingham in the past."

Another posted that the group "looks like a new and disturbing escalation of the division happening within the Greens NSW".

"We have been warned of the dangers of MPs wanting to control the party rather than the other way around. Is this internal democracy Jeremy Buckingham style?"

Fairfax Media has also seen several posts thanking organisers for establishing the "welcoming" group.

Mr Buckingham declined to comment.