Latest attack shows terror evolving: PM

The knife attack on a man in Sydney - committed the day before the 15th anniversary of the 9/11 terror attacks in the United States - shows how terrorism is evolving, Malcolm Turnbull has told parliament.

The prime minister said 9/11 was a complex and elaborate attack planned months in advance, whereas what occurred on Saturday was the work of a lone actor inspired by Islamic State online propaganda.

"We have to recognise that we will see more of these," Mr Turnbull said on Monday.