Detectives have charged two men with attempted murder over the stabbing of notorious underworld figure Tony Mokbel at Victoria's maximum-security Barwon Prison.

Key points: Mokbel is serving a 30-year prison sentence for drug trafficking

Mokbel is serving a 30-year prison sentence for drug trafficking The attack occurred in the same prison where gangland killer Carl Williams was bashed to death in 2010

The attack occurred in the same prison where gangland killer Carl Williams was bashed to death in 2010 Victoria's Commissioner for Corrections says she does not believe Mokbel's injuries are life-threatening

Mokbel was rushed to hospital in a critical condition following the attack at the prison at Lara, south-west of Melbourne, on Monday afternoon.

He was in a serious condition at the Royal Melbourne Hospital about 12:30pm on Wednesday.

A 31-year-old inmate was also attacked and taken to Geelong Hospital for treatment, before being released from hospital on Tuesday morning.

Armed Crime Squad detectives charged the two 21-year-old men with attempted murder, intentionally causing serious injury and causing serious injury intentionally in circumstances of gross violence.

The two men will appear in Geelong Magistrates' Court for a filing hearing on Friday.

Barwon Prison houses the state's most dangerous offenders and was where gangland killer Carl Williams was bashed to death with part of an exercise bike in 2010.

The ABC understands Mokbel suffered a stab wound to the chest during the attack, before he was flown to the Royal Melbourne Hospital, where he remained in a critical condition at 4:30pm on Tuesday.

Sorry, this video has expired GRAPHIC CONTENT WARNING: Paramedics treat Tony Mokbel after the prison attack

Mokbel, sentenced to 30 years in prison in 2012, was the mastermind behind an elaborate drug syndicate known as The Company.

Victoria's Commissioner for Corrections, Emma Cassar, said CCTV footage of the attack showed "punches and stabbing actions" as two men attacked Mokbel as he returned to his cell from the prison's main unit.

"Tony was certainly knocked unconscious [according to] the CCTV. Within seconds, and certainly I can say confidently under 10 seconds, the first staff member responded," she told ABC Radio Melbourne.

"They provided medical assistance to Tony Mokbel and quickly secured the two suspects who were taken away."

She said three makeshift weapons, known as shivs, were found and handed over to Victoria Police.

Mokbel is serving a 30-year prison sentence for drug offences. (AAP: Julian Smith)

The two suspects were separated within moments of the attack and have been moved into the high-security unit at the prison.

Despite Mokbel's critical condition, Dr Cassar said she did not believe his injuries were "life-threatening".

She said the other prisoner injured in the attack appeared to be going to Mokbel's aid in the footage.

On Sunday, the Sunday Herald Sun reported that Mokbel had emerged as a "powerful enforcer" in the prison, and had disrupted an extortion racket being run by Pacific Islander inmates.

The front-page story on Tony Mokbel was published a day before he was attacked. (Twitter: Nick Papps)

Dr Cassar said the two men seen attacking Mokbel on the CCTV footage were of "Pacific Islander background" and that it could be a "coincidence" Mokbel was attacked a day after the story appeared.

"There are some similarities between the two incidents … it may not be a coincidence [but] at this stage it's too early to make a comment on that," she said.

Victorian Premier Daniel Andrews on Tuesday said the Government was prepared to make any necessary changes to prison security in the wake of the incident.

"It doesn't matter what we might feel about that particular person, we want our prisons to operate properly and that means they need to be safe for everybody involved, and that includes staff," Mr Andrews said..

Sorry, this video has expired Why you should care about the Lawyer X affair

Mokbel recently returned to the headlines after it was revealed that his barrister, known as Informer 3838 or Lawyer X, was acting as a paid informant and was passing information to Victoria Police about her clients.

Victoria's Director of Public Prosecutions, Kerri Judd QC, has written to 20 criminals including Mokbel, whose convictions may have been affected by Victoria Police's use of the barrister as an informant.

Dr Cassar said Mokbel was "very confident he would get out of jail" and she suspected that would probably be very irritating to other prisoners.

The Victorian Government has called a royal commission into Victoria Police's management of informants.

Mokbel was disguised in a wig when he was arrested in an Athens cafe in 2007. (ABC News)

Mokbel famously skipped bail in 2006 while on trial for cocaine importation, and hid in Bonnie Doon in northern Victoria before being driven to Western Australia, where he set sail on a yacht, hidden in a secret compartment with its own toilet.

The yacht sailed across the Indian Ocean, through the Suez Canal and on to Greece.

Even while in hiding in Greece, Mokbel continued to run his drug syndicate, organising the trafficking of $4 million worth of speed.

Despite being disguised in a wig, he was arrested by Greek police in a cafe in a seaside suburb of Athens in June 2007, 15 months after fleeing Melbourne.

In 2012 he was sentenced to 30 years' jail with a minimum of 22 years.