Rodney Gene Crosswell, 26, was captured about an hour after his escape.

In November, Crosswell was sentenced to 10 1/2 years in prison for a string of serious offences, including shooting at a police woman with a sawn-off shotgun on the Brooker Highway in Hobart in May.

Prisoners had been held in the Ron Barwick Prison while repair work was completed on Risdon Prison, which had been closed due to a design flaw.

Mr McKim said prison officers were told to move prisoners back to Risdon Prison five days ago, but the Community and Public Sector Union refused to allow them to do it.

"Regrettably had inmates been returned to the Risdon Prison complex as soon as work was completed, the escape of this inmate today would not have occurred," he said.

"For the safety of the community, staff and inmates it was important that the inmates were returned to the Risdon Prison complex."

It sparked an angry response from the union, with assistant secretary Mat Johnston accusing Mr McKim of not taking workers' safety seriously.

"Nick McKim (needs) to stop blaming workers for the failings in the Tasmanian prison system and start accepting responsibility for his own incompetence," he said.

Mr Johnston said the escape was due to a failed system, which has seen 17 prison officers assaulted in the past year.

"Somebody should ask the minister why these maximum security prisoners were being held in a minimum security facility and who is to blame for the government paying millions of dollars to develop a new prison that is not fit for the purpose designed," he said.

Mr McKim said the dispute with the unions had been resolved at a hearing at the Tasmanian Industrial Commission in favour of the Department of Justice - just hours before the escape occurred.

Mr McKim said he had instructed prison management to enforce the order to move all maximum security prison inmates back to the Risdon Prison immediately.