Australia increased its terror alert for the first time in a decade, with Prime Minister Tony Abbott citing the threat posed by local supporters of Islamic State militants.

The National Terrorism Public Alert System was raised to high from medium, indicating the government and intelligence authorities believe an attack is likely, Abbott told reporters in Melbourne today. The increase to the second-highest level doesn’t mean an attack is imminent, he said.

Raising the alert will mean increased security screenings at airports, ports, government buildings and public gatherings such as major sporting events, including this month’s Australian football final in Melbourne that attracts up to 100,000 supporters.