Image copyrightEPAImage caption Australian police raided properties in Melbourne on Tuesday Australian police say they have arrested three men who were plotting to commit a terror attack in Melbourne.The group had been attempting to source a semi-automatic rifle to kill as many people as possible in a crowded place, authorities said.The suspects - aged 21, 26 and 30 - were allegedly inspired by the Islamic State group.There was no ongoing threat to the public, said Chief Commissioner Graham Ashton.Mr Ashton said the men had not settled on a location for the alleged attack, but their planning had "escalated" in recent days."They were certainly looking at a place of mass gathering, where there would be crowds, because they were trying to focus on trying to have a place where they could kill as many people as possible," he told reporters on Tuesday.Earlier this month, a knife-wielding attacker killed one man and injured two others in Melbourne in what police said was a terror attack.Mr Ashton said the suspects arrested on Tuesday had become "more energised" in the past week, but it was unclear whether this was due to increased public discussion about terrorism.

The three men, all Australian citizens of Turkish descent, were arrested in police raids in Melbourne's north-west on Tuesday.

Two are brothers, police said.The group had been tracked by authorities since last year and recently had their passports cancelled over fears they would engage in terrorism activity overseas, Mr Ashton said.Image copyrightGetty ImagesImage caption Police said the man planned to attack a crowded place somewhere in the city Police said the men had been in the process of acquiring a semi-automatic .22 calibre rifle.

They did not give further details."If we had not acted early in preventing this attack, we'll allege the consequences would have been chilling," said Australian Federal Police Assistant Commissioner Ian McCartney.The three men were expected to charged with terror-related offences later on Tuesday.Australia has strict gun laws which ban automatic and semi-automatic weapons and require gun owners to be registered.Since the nation's terror threat level was raised to "probable" in 2014, police have charged 90 people in counter-terrorism investigations.Fifteen suspected terror plots have been foiled in that time, according to authorities.