Election 2016: Greens volunteer allegedly bitten by Liberal in fight for Higgins

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The battle for the seat of Higgins has spilled into violence with police investigating the alleged biting of a Greens volunteer by a backer of assistant treasurer Kelly O'Dwyer.

Investigators have been told a 48-year-old woman was sitting in a car with a friend outside Armadale Public School on Densham Road about 9pm on Friday when two men -  aged in their 60s - approached her vehicle.

Pre-polling in Higgins: Kelly O'Dwyer with Jason Ball and Karl Katter. Photo: Jason South

The men allegedly made comments about election material for the hotly contested seat of Higgins, where a "green army" of volunteers spent the night capturing the best spots for election posters, before the woman attempted to take their photo.

A Victoria Police spokeswoman said a struggle took place, and the Greens volunteer was allegedly bitten, before the two unknown men drove off in a white SUV.

Police say the woman suffered "soreness to her thumb" following the incident.

Stonnington Greens branch co-treasurer Michael McCormack, a witness to the incident, said he and the alleged victim had been left in shock by the altercation with the two suspected Liberal supporters.

"Two men approached us in the car, upset the Greens had put posters and other things up - we're talking the heartland of Liberaldom here," he said.

"I wound down the window and they got aggressive. We had been advised that if we felt threatened by people we should take their photo. My fellow Green took out her phone to do that and the guy reached across me and grabbed her and was trying to pull her phone away."

Mr McCormack said a tussle ensued as she was pulled by the arm. When the man finally let his alleged victim go and stepped away, she realised she had been bitten on the hand.

"We were both pretty shaken, we quickly called the police and went down to Prahran police station and made a statement."

Mr McCormack said in the time it took to visit the police station about half of the Greens posters were ripped down.

No arrests have been made and the investigation remains ongoing.

A spokeswoman for Ms O'Dwyer denied the incident took place.

"The claims are completely false."

The election-eve incident follows an alleged altercation between Ms O'Dwyer's security staff and a Higgins voter who confronted the Liberal MP about asylum seeker policy at an early polling booth in Malvern on Tuesday.

The woman said she was asking whether Ms O'Dwyer supported children being held in detention when a security guard grabbed her by the hip and shoulder and tried to move her away despite her protestations.

A Victoria Police spokesman said "conflicting reports" had been made about the incident.

Greens candidate Jason Ball is hoping to make history by forcing the Liberals to preferences for the first time in the 59-year history of the seat of Higgins.