A prison inmate is on the run after escaping custody while visiting a medical facility in Auckland this afternoon.

Police warn that Te Ariki Poulgrain is dangerous and should not be approached. He has links to the Killer Beez gang.

Police say he may still be wearing prison handcuffs after escaping from custody at 1.30pm today.

Poulgrain was among a group of inmates who assaulted notorious double-killer Graeme Burton.

Poulgrain, 23, escaped from Corrections custody while visiting a medical facility in Grafton.

"Police are assisting Corrections with trying to locate him and have been making extensive enquiries to try to find him," police said.

"Police want to reassure the community we are doing everything we can to locate him."

Poulgrain is described as about 183cm tall and of thin build. Anyone who sees him is asked to ring 111 immediately.

He is considered dangerous and should not be approached.

"He has known links to the Killer Beez gang."

Poulgrain was among a group of three prisoners who assaulted notorious double-killer Graeme Burton at Auckland's Paremoremo - the prison that houses the country's most dangerous criminals.

Poulgrain stabbed Burton at least seven or eight times during the assault.

Justice Geoffrey Venning sentenced Poulgrain to three years and nine months' imprisonment for his role in the brutal attack.