THERE will be a full investigation into tram inspectors who forcefully restrained a fare-evading university student, pressing a knee to his throat as they held him under a bench, Transport Minister Terry Mulder says.

The dramatic arrest marks a change of tactics for authorised officers on Melbourne's tram network, after they were told earlier this year that they must not detain offenders.

Michael Liu, 20, said he was traumatised and struggling to sleep after he was confronted by several inspectors at the Lincoln Square tram stop on Swanston St last week.

He admitted he was fare-evading as he travelled just two stops to Melbourne University, but he said he was shocked by what happened next.

"They grabbed my arm and that really scared me. Maybe they thought I was going to run, and I said to calm down," he said.

Mr Mulder admitted that the confrontation "was not a good look", but also defended the ticket inspectors.

"I still point to the fact that if you're stopped by an authorised officer on public transport and you're asked to provide your myki then you just need to comply to that and nothing will escalate," he told 3AW radio today.

Mr Liu said he was not carrying a driver's licence, but Yarra Trams spokesman Adam Woolcock claimed Mr Liu had refused to provide his name and address.

"He then attempted to leave the scene before the report could be completed. He continued to walk away and an officer then took hold of him and reminded (him) that he was under arrest," Mr Woolcock alleged.

Mr Woolcock said officers called the police when the student allegedly started "pushing officers violently with his hands".

Mr Liu was restrained on the ground under a bench as witnesses including Nathan Tonkin ran to the commotion.

"They told me to back away but I thought it needed to be filmed," Mr Tonkin said.

"One of the guys had his knee pressed against his neck, another one of them had his arm wedged up against the seat, like they were trying to snap his arm."

Mr Liu screamed that he couldn't breathe and he said his left wrist was severely bruised, making it difficult for him to prepare for his university exams.

Public liability lawyer Dimi Ioannou said Mr Liu could have a right to sue the inspectors over his treatment.

"Inspectors must know the difference between restraint and excessive force and appreciate that they don't have the same powers as Victoria Police," Ms Ioannou said.

Her firm Maurice Blackburn represented Tim Vivoda in a case earlier this year where he was awarded almost $130,000 after he was punched in the head by a police officer at a station.

Ms Ioannou said Mr Liu could have a similar claim if he could "prove that the actions of the ticket inspectors were an intentional act designed to cause injury".

"This disturbing video footage confirms there needs to be further training implemented for ticket inspectors in order to handle fare evaders in a way that does not leave them injured," she said.

"The State Government has in the past been criticised for not taking an active role in overseeing the system and public transport operators are criticised for failing to report incidents. It's time for action on this now."

Herald Sun readers are divided over the incident.

Jamie said: "Those inspectors need to face disciplinary actions. They went way too far!"

Vilo agreed, saying: "I think you need to reread the article people - knee to throat for $2.20.

Let's be realistic in a modern day western world. Knee to throat for $2.20? What next we going to start throwing fruit again at the stocks??? Evolve already."

But Brian was on the side of the tram officers, saying: "Oh, boo hoo. Just pay your fare."

Chris agreed: "If he had paid the fare he wouldn't be in this position, only got himself to blame. No sympathy for people who break the law then play the victim."

In March, authorised officers received a memo saying that "an arrest must be an absolute last resort".

"Authorised officers must not block the path of, or attempt to physically detain a person who attempts to walk/run away," the memo said.

"(They) must not surround or corral any person being spoken to regarding an offence."

Mr Woolcock said that memo was in response to "a spate of serious injuries sustained while they carried out their duties".

He said the policy was regularly reviewed and officers were reminded in July that they had a legal right to make an arrest if required.

Fare evasion costs about $60 million each year and Mr Woolcock said Yarra Trams was committed to catching offenders.

One authorised officer was taken to Epworth Hospital for treatment after he injured his hand.

Mr Liu could be charged by the Transport Department after they receive a brief of evidence on the incident from Yarra Trams.