The New South Wales Greens party has broken out into civil war in the middle of the election campaign following Carole Medcalf's ousting as the party's executive officer.

Key points: Former executive officer Carole Medcalf ousted, takes action in the Fair Work Commission

Former executive officer Carole Medcalf ousted, takes action in the Fair Work Commission Longstanding NSW Greens treasurer, Chris Harris, steps down over the handling of the dispute

Longstanding NSW Greens treasurer, Chris Harris, steps down over the handling of the dispute Dispute part of a broader struggle for control of the NSW party between the hard left and the moderates

The party's long-term treasurer, Chris Harris, has resigned over Ms Medcalf's treatment, and in an email to members he has accused the party of acting like a major bank trying "to shaft their customers".

Ms Medcalf was hired to professionalise the party and act as campaign director.

Senior federal Greens have told 7.30 they are dismayed by Ms Medcalf's departure and the rift in the state organisation.

For years there has been a bitter dispute for control of the NSW party between the hard left, known as the watermelons (green on the outside, red in the middle), and the moderates, who backed Ms Medcalf.

Actions 'reminiscent of tactics used by major banks'

Mr Harris has written an explosive email to Greens members informing them he has resigned as treasurer over Ms Medcalf's treatment, because he believes he has been "ethically compromised" by the actions of the party.

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He wrote that the Greens' tactics toward the executive officer were "reminiscent of tactics used by major banks to shaft their customers".

Mr Harris has held state executive positions with the Greens going back almost 20 years, as well as being a Sydney City councillor.

He also helped coordinate the campaign that resulted in the party's first state Lower House MP, Jamie Parker.

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In his email, Mr Harris said the party's treatment of Ms Medcalf had the potential to damage the federal party's campaign on industrial relations, which federal Greens leader Richard Di Natale has been pushing.

"The campaign to undermine, discredit and bully the executive officer flies in the face of our four principles, and makes a mockery of what we are saying to the electorate about our commitment to workers' rights," he said in the email.

Mr Harris declined to discuss his email with 7.30.

NSW party distracted by the dispute

Former executive officer Carole Medcalf took the party to the Fair Work Commission. ( Supplied )

Ms Medcalf began action against the party in the Fair Work Commission last November.

7.30 understands she signed a separation agreement last Monday and finished work at Greens headquarters on Wednesday.

When approached by 7.30, Ms Medcalf insisted she still worked for the party.

7.30 understands the settlement was between $90,000 to $100,000, and key areas of the separation agreement are still in dispute.

Ms Medcalf is a former Greens candidate who has been active in the party for more than two decades.

Documents obtained by 7.30 show the brawl over Ms Medcalf has been an issue since Prime Minister Malcolm Turnbull announced the federal election on May 8.

That weekend the Greens State Delegates Council (SDC) was meeting, and 7.30 has been told the employment dispute rather than electoral strategy was a key issue.

A group called the Inner Sydney Greens (ISG) proposed a motion calling on the party to seek to amicably resolve its dispute with Ms Medcalf.

Two previous attempts at mediation ordered by the Fair Work Commission had failed.

ISG is unhappy that the dispute is "dragging on for months … It appears the CoM [Committee of Management] has been unable to reach any decision that will protect GNSW from either maladministration during this important electoral period or from public embarrassment and electoral damage due to GNSW being unable or unwilling to comply with its duty as an employer."

That motion was defeated.

A rival motion proposed by convenor Hall Greenland that the SDC authorise party management to pay out Ms Medcalf was passed by the delegates.

Greens sources said there was anger at the industrial relations policies that led to the dispute and the fact that so much money was spent in the middle of an election campaign.

When 7.30 asked Mr Di Natale about the conflict, he said it was a matter for the NSW party and he knew nothing about it.

Mr Greenland and Greens senator Lee Rhiannon were both contacted but declined to comment.