The 53-year-old's condition improved from critical to serious on Wednesday as he remained in hospital two days after being stabbed by a pair of fellow inmates at Victoria's maximum-security Barwon prison.

Two men, aged 21, have been charged with attempted murder and other offences over Monday's vicious attack on Mokbel and another prisoner who went to his aid.

Police and prison authorities are investigating what sparked the attack, which occurred a day after a newspaper reported Mokbel recently intervened in a standover racket run by Pacific Islander inmates.

Prison authorities previously confirmed Mokbel was stabbed with makeshift knives, or shivs and the Herald Sun on Wednesday reported one of the weapons was hidden in a zucchini at the time of the attack.

Mokbel had just seen a visitor and was walking past other inmates celebrating a birthday when the pair launched the attack, the newspaper reported.

The second victim, aged 31, is back in Barwon after spending Monday night in Geelong Hospital.

Corrections Commissioner Emma Cassar said it was too early to say what prompted the assault, including whether there was a powerplay within the jail.

Premier Daniel Andrews on Wednesday said his government was prepared to make changes to prison operations pending the outcome of investigations.

"We do have to wait for the inquiry to run its course, find out exactly what happened, establish the facts, and if we have to do things differently then we stand ready to make changes that review tells us are necessary," he told reporters in Melbourne.

The two alleged attackers have been charged with attempted murder, intentionally causing serious injury and causing serious injury intentionally in circumstances of gross violence.

They will face a filing hearing in Geelong Magistrates Court on Friday.

Australian Associated Press