Sydney teenager arrested for planning terror act

A Sydney teenager has been arrested for planning an "imminent" terror attack.

Tamim Khaja, 18, was arrested at Macquarie Park in Sydney's north-west this morning.

"We are satisfied that this individual was acting alone," Acting Deputy Commissioner Neil Gaughan said.

"We will allege that this individual was looking at possible sites in Sydney to undertake a terrorist attack and was making arrangements to acquire a firearm.

"This young person's life changed today."

The teenager has links to others who are already before the courts on terror-related charges, Mr Gaughan said.

Khaja was prevented from leaving the country in February by police who intercepted him at Sydney Airport.

It's alleged he planned to travel to Syria but was unable to do so because his passport had been cancelled.

He is expected to face Parramatta Local Court on Tuesday afternoon.

The arrest is not related to the terror raids carried out in Melbourne this morning.

NSW Police Deputy Commissioner Catherine Burn said the latest arrest was one of nine alleged planned terror attacks police had prevented as part of the ongoing Operation Appleby.