A Sydney teenager has been arrested on suspicion of preparing to commit a terrorist attack and trying to travel to Syria.

Police said an attack was “imminent” when they arrested the Macquarie Park man, 18, on Tuesday.

The teenager’s Macquarie Park home, where he lives with his family was raided by police on Tuesday.

Australian federal police (AFP) assistant commissioner Neil Gaughan said: “We will allege he was looking at possible sites in Sydney to undertake a terrorist attack and was making arrangements to acquire a firearm,”

“We are satisfied this individual was acting alone.”

They allege the man, who had his passport cancelled, was turned away from Sydney airport in February after trying to leave the country.

The man was known to police for at least a year but not involved in any official deradicalisation programs.

“This person’s life changed today … He’s looking at life in prison,” Gaughan said.