Aussies warned be cautious in Istanbul

Australians visiting Istanbul have been warned to avoid the nightclub district as the manhunt continues for a gunman who opened fire on New Year revellers.

In what is believed to be a terrorist attack, the gunman dressed in a Santa Claus costume shot his way into the Reina nightclub.

At least 39 people, including many foreigners, were killed and 69 were wounded.

The Department of Foreign Affairs and Trade on Monday updated its travel advice for Turkey.

"Avoid the area, exercise heightened caution and remain vigilant to your personal safety and surroundings," the Smart Traveller website says.

It advises people to reconsider the need to travel to Ankara and Istanbul.

Acting opposition leader Chris Bowen condemned the "barbarous" attack and expressed sympathy for the victims and their families.

DFAT has not received any reports of Australians being caught up in the attack.