Federation Square in Melbourne, Australia
Federation Square in Melbourne, AustraliaiStock

Australian authorities have foiled a terrorist attack that was planned for New Year’s Eve, local police said Monday, according to AFP.

An Islamic State (ISIS) sympathizer planned to buy a gun and kill as many revellers as possible on New Year's Eve in Melbourne's popular Federation Square, they said.

The 20-year-old, who was born in Australia to Somali parents, was detained in a raid on a house in the Melbourne suburb of Werribee on Monday.

Police say he accessed a guide book online produced by Al-Qaeda on how to commit terror acts and use firearms, but was arrested before he could purchase an automatic rifle.

"What we will be alleging is that he was intending to use a firearm to shoot and kill as many people as he could in the Federation Square area on New Year's Eve," said Victoria Police Deputy Commissioner Shane Patton, as quoted by AFP.

"It is a tremendous concern to us that (during) the festive season, when people are out enjoying themselves, that there is a potential plot to commit a terrorist act. That is a huge issue for us but that is why we put the resources in," he added, stressing the arrest meant the threat "has been removed".

Federation Square is in the heart of Melbourne, opposite busy Flinders Street train station and St Paul's Cathedral. It is one of the most popular places to see in the new year and would be packed on December 31.

Australia raised the terror threat alert level to high in September of 2014, the same month on which it arrested 15 terror suspects who were planning to behead a random member of the public in a campaign of terror.

Since that time, 74 people have been arrested in 347 counter-terror investigations.

Only a year ago, police prevented another attack in the same area on Christmas Day, arresting several men who planned to use explosives, knives and guns to target the location.

A month earlier, in November of 2016, ISIS claimed responsibility for an attack in Melbourne.

Last August, Australian authorities nabbed a terrorist cell which plotted to bring down a plane.

Patton said the man, who lived with his parents, had been on their radar since the beginning of the year, part of a small community of extremists that police have been monitoring.

His behavior had gradually escalated over time, but police believe he was acting alone.

"The potential of the attack was catastrophic," said Patton, adding that the man was an "Islamic State sympathizer".

Asked if he had been inspired by last year's Christmas Day plot, Patton said how he became radicalized was still being investigated.

"We will be exploring where this person of interest got the idea from. Certainly, he becomes particularly energized when he sees other activities in the terrorist arena occurring," he said, according to AFP.