ACT Policing said the victim was walking along Hannaford Street from Belconnen Mall when someone ran up and grabbed him from behind and held a weapon, possibly a machete, to his throat.

The robber demanded money and pushed the man to the ground and he was then held to the ground by two other men.

The three offenders ran off towards the Page shops with a small amount of cash, an iPhone and the victim's black backpack.

The victim called police to let them know he had just been robbed.

Around the same time, police responded to an incident on Petterd Street at 10.35pm where a man was reportedly seen carrying a machete.

He was with two other men, and although he and one other managed to escape, officers were able to detain the third man, according to a police statement.

The first offender is described as Caucasian and aged in his 40s. He was wearing a light grey hoodie and dark track pants and carrying a long knife, possibly a machete.

The second and third offenders were both believed to be in their mid-20s and are described as Caucasian.

One was a wearing a dark hoodie while the other was wearing a green one. Both were wearing dark pants.

Witnesses or anyone with information is urged to contact Crime Stoppers online or by calling 1800 333 000.