Control orders are working, says AFP

Federal police say they have seen a change in behaviour in at least two people subject to anti-terrorism control orders.

Four Australians in the past 16 months have been placed under orders that restrict their movements and communication to help prevent a terrorist attack.

It's one of many controls at the AFP's disposal but according to AFP Assistant Commissioner Neil Gaughan, the most effective.

He said authorities had found a "twofold change" in behaviour with respect to two standing orders.

"One, in that the persons are no longer associating with people that we would consider undesirable," he told a joint parliamentary committee in Canberra on Monday.

"And secondly, that those people appear to ... be going down a different path, ie. employment, listening to their family members, listening to what we call respectable members of the community."

He said it was still early days but put down the change in behaviour mainly to the fact those people had received some sort of "different" religious views.

"And therefore they've realised the views they've previously had aren't the right ones," he added.

The committee on intelligence and security is looking into a bill that proposes lowering the age for which control orders can be applied from 16 to 14.