UPDATED 12.48pm: A warning to Australia not to be overly concerned about a terrorist attack.

The Australian Government is considering raising its terror threat level from medium to high, meaning a terrorist attack is considered 'extremely likely'.

University of Sydney terrorism expert Justin Hastings told Newstalk ZB's Mike Hosking Australia is a natural target.

"Australia is a Western country, Australia is actively involved in actions overseas and to that extent it makes them a target."

But Dr Hastings says any raising of the threat level without concrete evidence of a threat, will be nothing but scaremongering.

Islamic State hasn't proven itself in the West

The ability of the Islamic State to attack the West is being questioned.

Hastings says the Islamic State has proved its ability in the Middle East, but not elsewhere as yet.

"We want to be careful about saying, 'well, they can do this here in Syria and Iraq, but can they actually extend their attacks beyond their base'."

Dr Hastings says the organisation's ability to take territory quickly has been most alarming.