Sydney may have permanent anti-terror measures in the CBD

Semi-trailers and concrete bollards were used to block streets around Pitt Street Mall, George Street and Elizabeth Streets during the Boxing Day sales in the CBD in Sydney. Photo / AAP

Sydney may have permanent anti-terror measures in the CBD after Boxing Day crowds shopped amid trucks, cranes and bollards.

The measures, in addition to road closures yesterday, were put in place as thousands flocked to the CBD to browse post-Christmas sales.

It follows last week's vehicle attack in Melbourne's bustling Flinders Street which hospitalised 20 people, including two men who area still fighting for life.

NSW Police Assistant Commissioner Mark Walton described the tactics as an "escalation" of the usual crowd protection strategies.

Although the national terror threat level had remained at "probable" for over two years, he said there was still a need for vigilance.

"We would be negligent not to look at our days when we do have a lot of people loaded in these areas and put some treatments in," Walton told 2GB today.

"You've only got to look at what's happened internationally and even down in Melbourne to know people are vulnerable and we need to do what we can, within reason, to make them safe in these areas."

Walton also cited a national strategy for protecting crowded spaces, released by Prime Minister Malcolm Turnbull in August, which requires landholders to consider security with advice from police.

"We really do need to mature in relation to the way we build structures around our footpaths and roadways," he said.

"I was in London a month ago - there's significant treatments all through London.

"I hope we don't get to that point but I do believe there are some permanent structures that will be required in Sydney and other locations."

The barriers and road closures were removed after Boxing Day, however the next major challenge for authorities will be New Year's Eve.

Walton said police had spent months planning a huge security operation.

"There are a lot of measures that are already starting to go in around the city around how we manage the crowds and protect the crowds on New Year's Eve," he said.

- AAP