Prison guards have killed at least 17 prisoners after a mass breakout at a jail in Papua New Guinea (PNG), according to reports, with dozens of inmates still on the run.

The incident took place in Buimo jail in the Pacific nation's second-largest city, Lae, on Friday, but only became public after media reports on Monday.

"Unfortunately these incidents, tragic as they are, happen all too frequently in Papua New Guinea as there is poor accountability with police and security officers," Kate Schuetze, Amnesty International's Pacific Researcher, told the Reuters news agency.

The PNG Post-Courier and The National newspapers both cited local police as confirming 17 people were killed, three were caught and 57 were still at large.

"These are undesirable people and will be a threat to the community," Lae police metropolitan commander Chief Superintendent Anthony Wagambie Jr said of those who escaped, warning the public to be vigilant.

"The majority of those who escaped were arrested for serious crimes and were in custody awaiting trial.

"A good number were arrested by police last year for mainly armed robberies, car thefts, break and enter and stealing."

Buimo is the same prison where police shot dead 12 inmates during a jailbreak last year. The jail, one of the largest in the country, has been criticised in the past for overcrowding and for poor prisoner conditions.

Wagambie urged family members and associates of the escapees not to harbour them.

"I am warning them that they will be caught. They must do what is good for them and surrender," he said.