A young woman attaches herself to a car with cement during the third and final day of anti-war protests in Melbourne

A young woman has been arrested by police after sticking her arm to the back of a car during the latest day of anti-war protests in Melbourne.

The activist is believed to have stopped a vehicle on the bridge near the Melbourne Convention and Exhibition Centre at around 7.30am on Friday.

It is believed that he then opened the trunk, placed his own hand in a bag of cement and proceeded to fix his arm to the car.

Traffic was brought to a standstill as drivers in the surrounding area were forced to stop.

Police were seen using bolt cutters and a chisel to separate the woman’s hand, which was trapped in the concrete, from the trunk of the car.

There have been up to 50 arrests in the past three days of protests in Melbourne’s CBD and police are braced for further potential violence.

Protest organisers expect “significant protest activity” on Friday when the Land Forces weapons exhibition draws to a close in Melbourne after days of unrest.

“There will be a renewed vigor to protest because it’s the last day,” said organizer Caroline Da Silva.

Police were forced to cut his arm off the vehicle using a chisel and bolt cutters.

“This is our last chance to show these weapons companies that they are not welcome here.”

The first day of the exhibition, on Wednesday, erupted in violence and chaos as rubbish bins were set on fire and horse manure, food acid and “missiles” made from glass bottles were thrown at police barricades.

Riot police returned fire on the 1,500 protesters with rubber bullets, tear gas and stun grenades, leading to the arrest of 42 people.

But the scenes were calmer on Thursday as a few hundred protesters marched toward the convention center before dispersing.

They later regrouped outside the Bourke St offices of defence contractors Hanwha Defence and Elbit Systems to oppose deals between the companies and governments, blocking access to cars and trams.

Protesters say the weapons on display at the exhibition have been used against civilians in the Gaza conflict.

Police and political leaders condemned the “shameful” actions and tactics used by the activists, calling them “thugs.”

Police Commissioner Shane Patton lashed out at “hypocritical” protesters and warned that the largest deployment of officers in two decades would be prepared for any event during the conference.

Patton’s allegations have not deterred activists, and Da Silva vowed that protesters would “be there to stay for a long time.”

“A little bit of police spray, a few rubber bullets, those things are harmful, but they do nothing to alter our consciousness,” he said.

“We are here because we are people of good will and good spirit who want to see peace, justice and freedom, so there is nothing that police violence can do to change that.”