Russell Street bomber Craig Minogue has been banned from calling an interstate associate who has been running the killer's Twitter account.
Minogue has been tweeting for almost a year via proxy, including about the jail stabbing of drug lord Tony Mokbel in February.
Corrections Minister Ben Carroll said Minogue's contact was no longer on the approved callers list, and other prisoners trying the same thing would face similar bans.
"Prisoners do not have direct access to the internet, but we have found a loophole where they can use their telephone rights to then ask an independent third party to upload information to the world wide web," Mr Carroll told reporters.
"Right now we're updating our corrections regulations to insert a new offence, where prisoners using third parties independently to access social media will have certain privileges taken away, whether it be phone access or their outside prison time in the general yard."
Mr Carroll has also written to federal Attorney-General Christian Porter and Home Affairs Minister Peter Dutton, who oversee the national criminal code, asking to create an offence targeting those third parties assisting prisoners from interstate.
Prisoners will still be able to phone and write to people but the problem with social media is publishing on the internet.
In February, opposition corrections spokesman David Southwick tweeted, and since deleted, a screenshot of Minogue's Mokbel tweet: "That in Daniel Andrews' Victoria, we are relying on convicted killer Craig Minogue to tell us what is going on in our prisons, speaks volumes."
On Thursday, he said the Liberals had for months been calling for action.
"A violent prisoner like Craig Minogue should not be able to tweet out on a regular occurrence, like some sort of Hollywood movie actor," he told reporters.
"This is something that goes beyond belief."