A US Embassy official has been robbed at gunpoint in Port Moresby after being stopped at a police roadblock.

Key points: A man in civilian clothes, who was with the police, produced a pistol and took the American's phone, watch

A man in civilian clothes, who was with the police, produced a pistol and took the American's phone, watch Official was forced to drive to an ATM and withdraw cash from his bank account

Official was forced to drive to an ATM and withdraw cash from his bank account Victim is not believed to have sustained is any significant physical injuries

Several sources have told the ABC the male official was driving home on Friday night after having dinner at the popular Harbourside restaurant precinct when he was stopped at a police roadblock a short distance away.

A man in civilian clothes, who was with the police, got into the car, produced a pistol and took the American's phone and watch.

The official was then forced to drive to an ATM and withdraw cash from his bank account.

He was able to get away when the armed robber got out of the car while it was parked near a nightclub in the CBD.

The victim was left traumatised by the ordeal but is not believed to have sustained any significant physical injuries.

The ABC has been told the US Embassy has put a nightly curfew in place for its staff following the robbery.

One source said the official's car did not have a duress alarm, which is a common security feature in diplomatic vehicles in Port Moresby.

A spokeswoman for the US Embassy confirmed there was "an incident involving a member of the embassy community".

She declined to comment further, citing ongoing investigations.

Police officers 'rounded up'

Police say they are investigating the robbery and have identified a suspect.

A spokesman says they have requested CCTV footage from the ATM where the victim was forced to withdraw money.

He says investigators have also "rounded up" officers who were on duty in the area at the time of the robbery for questioning.

The incident occurred as the PNG Government prepares to host the APEC Leaders Summit in Port Moresby next year.

The Australian Government is providing more than $100 million to support the preparations.

That support includes training for the local police by the Australian Federal Police, and the provision of new equipment including cars, motorcycles and jet-skis.