Drug Kingpin Tony Mokbel's Condition Improves After Prison Stabbing

Tony Mokbel's condition has improved from critical to serious after he was stabbed at Barwon prison.

Two 21-year-old inmates have been charged over Monday's attack on Mokbel and another prisoner who went to his aid.

On Wednesday morning, a hospital spokeswoman confirmed 53-year-old Mokbel remained critical but by lunchtime, his condition had improved to serious.

Mokbel being attended to by medical staff after an alleged stabbing at Barwon Prison, Victoria (AAP Image/Supplied by Nine News)

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

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

It is thought Mokbel was injured by a group of prisoners who were celebrating the 21st birthday of another inmate. The group had been eating cake and drinking soft drink when Mokbel walked past. A police spokesperson confirmed to 10 News First that one of those charged was the man celebrating his birthday.

They will face a filing hearing in Geelong Magistrates' Court on Friday. The second victim, aged 31, is back in Barwon after spending Monday night in Geelong Hospital.

Horty Mokbel (left) and associates of Tony Mokbel are seen inside Royal Melbourne Hospital on Tuesday (AAP Image/Stefan Postles)

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

Most of Barwon Prison remained in lockdown on Tuesday, before normal evening and overnight restrictions kicked in.

Dr Cassar said the lockdown was necessary while authorities investigated the incident and whether any reprisal attacks were likely.