Papua New Guinea police believe the theft of 800 thousand US dollars from a bank in Madang was undertaken by the same gang which robbed a bank in Gulf Province in May.
Heavily armed thieves, dressed in police uniforms, took two Bank South Pacific staff and the branch manager and his family hostage on Friday night before robbing the bank the next morning.
Police were alerted to the robbery late on Saturday and the hostages were freed from a Madang hotel.
A police spokesman says the modus operandi is the same as used in the robbery of the bank's branch in Kerema in May, when around four hundred thousand US dollars were taken.
He says suspects in the earlier robbery had also been sighted in Madang late last week.
A major police hunt for the robbers is underway - a car used in the heist has been found in Lae.