He added that Serco had run Mt Eden with so few staff it needed 50 extra people "just to make it safe".
"And it still doesn't bring it up to proper safe staffing levels; they probably need another 50."
However, staff were "getting control of the prison back", "You can look at the prisons with the highest assault rates - Rimutaka Prison, which is constantly in the news, [is] constantly short-staffed, it's constantly having shifts not replaced.
"Yesterday's announcement that the contract with Serco would be cut short in 2017 was "a wet bus ticket", Mr Hanlon said.
"This shows, contrary to what the Prime Minister says, that there is no accountability for privatisation. These private corporations give our Government the runaround."
He added: "We're now in a ridiculous situation where to get accountability we've got to wait 15 months for the break clause in the contract. If there was true accountability they would kick them out now.
"In the public sector there's true accountability because they can say to their prison managers, 'that's not acceptable, go find another job'. And our question is, 'why aren't these people being held accountable?'."
The Government could "easily" pull out of the contract with Serco, Mr Hanlon said.
"[The contract] talks about how you can kick them out for performance as well as the break clause. The Government are just too scared to do it."
The Government was afraid of being dragged through the courts by Serco, he said.
"There would be nothing more embarrassing to them than saying, 'this is poor performance, we're kicking you out', then getting taken to court and Serco winning."
"So this is just face-saving on [the Government's] behalf."