The Australian government says a decision to change the country's terrorism alert system has not been prompted by any new terror threats or warnings.

Under the current system if the terrorist threat level is changed, it has to be nation-wide.

As of today, the government will be able to apply an alert to a specific jurisdiction, industry, business sector or location

The attorney-general, Robert McClelland says the increased flexibility will avoid disrupting people or businesses not directly affected by a threat.