Police say a teenager has been arrested after officials alleged that he had been planning to launch a terrorist attack in Sydney.

The Australian Federal Police said Tuesday that the 18-year-old would be charged with planning a terrorist attack and preparing to enter a foreign country to engage in hostile activities. If convicted, he could face a maximum sentence of life in prison.

Australian Federal Police Acting Deputy Commissioner Neil Gaughan said officials believe the teen was working alone, and had been making arrangements to get a firearm.

Police declined to detail what the alleged plans involved, including what sites were the proposed targets.

Australia's government raised the country's terror threat level in 2014 in response to the domestic threat posed by supporters of the Islamic State group.