Business as usual but be alert: Bishop

Australians shouldn't change their behaviour during the festive season, but they should remain alert to the possibility of a terrorist attack, Foreign Minister Julie Bishop says.

Prime Minister Tony Abbott has said there has been a heightened level of "terrorist chatter" in the aftermath of the fatal Sydney siege.

The terror threat level remains at high, meaning an attack is likely.

"It's not at the next level - extreme - which means imminent, in other words (security agencies) have details of an attack that is likely to take place," Ms Bishop said.

"We're just warning people to be careful, be alert but of course go about your everyday business."

About 300 troops were mobilised in France overnight after several "lone wolf" attacks but when asked whether the government had similar plans, Ms Bishop said their situation was "a little more dire".