Aust terror threat level raised to high

AUSTRALIA RAISES NATIONAL TERRORISM PUBLIC ALERT LEVEL TO HIGH:

* It's the first time the level has been raised to high.

* The level is higher than following the September 11 attacks in 2001 and the Bali bombings in 2002.

* Means a terrorist attack is considered "likely" but not "imminent".

* There will be more security at airports, ports, military bases, government buildings and large public events such as this weekend's football finals.

* Security authorities have no specific intelligence of advanced plots, but there has been a sixfold increase in counter-terrorism operations during the past 12 months.

* Outgoing ASIO boss David Irvine says the security threat could manifest itself into "another Bali attack" or attacks by "loners or groups".

* They have recommended the cancellation of about 50 passports so far, including people as young as 17.

* The decision was based on a body of evidence - including the number of Australians fighting or supporting extremist Islamic groups in Syria and Iraq - that points to the increased likelihood of a terrorist attack.

* ASIO says Australia's likely support for a US-led coalition to destroy Islamic State in Syria and Iraq was not a factor in the decision to raise the alert level.

* State premiers and the federal opposition were briefed about the decision before its announcement.

* Members of the public can report suspicious activities to the National Security Hotline on 1800 123 400, or directly to local police.