Police are searching bushland near Risdon Prison for escaped inmate 38-year-old Graham John Enniss.
Detective Inspector Jason Elmer said Enniss and another inmate had accessed the roof of a building inside the prison facility at 8.30am on Monday.
He said the other man, who was not identified, was captured by prison staff and taken back into custody while Enniss cleared boundary fencing.
Detective Inspector Elmer said Enniss was last seen heading south of the prison into bushland near Geilston Bay.
"We have deployed numerous police resources into the area in an attempt to location Mr Enniss, including a helicopter," he said.
"We currently have police in the area conducting doorknocks."
Detective Inspector Elmer said police would conduct vehicle checks in the immediate area.
Enniss is serving a substantial prison sentence for incidents committed on the North-West Coast, including violent acts towards police.
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Detective Inspector Elmer warned members of the public not to approach the prisoner, and if seen, to contact police immediately.
He could not detail the security arrangements around Enniss and his fellow inmate at the time of the escape.
Enniss is about 180 centimetres tall, of medium build, and has 'thug' tattooed across his neck.
He is wearing black pants and a green prison-style shirt.
Bass Liberal MP Michael Ferguson said it was important the government let state authorities manage the situation.
"Clearly there will be lessons learned out of this," he said.
"It's highly unusual to see someone escaping from the prison and I know the Tasmanian Prison Service will be taking action once those lessons are fully understood."