Victorian Greens MP Sam Hibbins stepping down from party after ...

The leader of the Victorian Greens says she was forced to suspend an MP and remove him from the party room following "serious" allegations of inappropriate behaviour.

Earlier on Friday, Victorian Greens MP Sam Hibbins announced he was stepping down from the party room after admitting to having a relationship with a staff member from his office.

Sam Hibbins has held the seat of Prahran in Melbourne's inner south-east since 2014, and said he had breached party room rules by entering into the relationship.

Sam Hibbins served as co-deputy leader of the Victorian Greens until his suspension on Tuesday. (Facebook: Sam Hibbins)

"I recognise this was a significant error of judgement and understand the distress this has caused," Mr Hibbins said in a statement.

"This short relationship ended some time ago, but it does breach our party room rules."

Mr Hibbins, who served as co-deputy leader of the Victorian Greens, said he would leave the party room to make amends and focus on his family. 

The 42-year-old is married and has two children. 

Sam Hibbins' office was closed to the public on Friday. (Supplied)

"I deeply regret what has happened. I have made a very human mistake, but I am working to find the best way forward," he said.

The member for Prahran said the relationship had ended "some time ago" and was consensual.

Shortly after his announcement, his profile was removed from the Victorian Greens website and his personal website was taken offline.

Mr Hibbins will continue to sit in state parliament as an independent MP.

Victorian Greens leader Ellen Sandell held a press conference on Friday to address the allegations and strongly condemned Mr Hibbins' behaviour.

"The Member for Prahran has completely lost my trust, and the trust of his Greens colleagues, the Member for Prahran will never be welcome back in our party room," Ms Sandell said.

"I don't think that he meets the standards of behaviour expected of any MP."

Ellen Sandell says the party was only made aware of the allegations on Tuesday. (Supplied)

Ms Sandell said she was notified of the allegations on Tuesday night by the Department of Parliamentary Services, who she said reported "inappropriate behaviour" over a period of time. 

The Greens leader said due to the small staffing of the party, more details about the time period or nature of allegations could not be divulged for fear of revealing the staff member's identity.

According to Ms Sandell, she held a meeting with Mr Hibbins on Tuesday evening where he confirmed some of the allegations and contested others, before being suspended.

"I accept the error in judgement in having a consensual relationship. I refute any suggestion beyond this, that has come after the relationship has broken down," Mr Hibbins told the ABC.