The consulate warned travellers to pay "particular attention to their surroundings" in congested and popular tourist areas.

"Be aware of your surroundings; and practice sound personal security and situational awareness," the alert reads.

It urges people to "avoid demonstrations and areas with significant police activity, review their own personal security plan, and stay alert".

Yixuan Cheng, Pikria Darchia, Jade Young, Dawn Singleton, Ashlee Good and security guard Faraz Tahir all died in the attack by Queensland 40-year-old Joel Cauchi at the shopping centre on Saturday, April 13.

Three people including a nine-month-old child remain in intensive care after the stabbing attack.

The attack has been linked to Mr Cauchi's mental health with terrorism ruled out.

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The father of Mr Cauchi, Andrew Cauchi, told reporters outside his Toowoomba home in Queensland he was "extremely sorry" to hear of his son's actions.

He explained his son may have targeted women due to this frustration over wanting a girlfriend, but having no social skills.

"To you he's a monster, to me he was a very sick boy," he said.