The head of the Returned and Services League of Australia says larger than usual crowds expected at Anzac Day services around the world show Australians don't abide threats.

Rear Admiral Ken Doolan, National President of the RSL, will spend Anzac Day at Gallipoli as part of an official delegation including the Prime Minister. He said crowds worldwide were already expected to swell, being a centenary year, but after an alleged plot to attack police at a Melbourne commemoration was foiled, there was an added element of defiance.

"Australians don't take kindly to being threatened by fringe groups," Rear Admiral Doolan said.

"How dare they be so disrespectful of the great benefits they enjoy in our society, of freedom of speech and freedom of association. These freedoms have been paid for by blood.

"Not only will the RSL go ahead with all their marches, we encourage everybody to turn out and show what a strong and robust country we are. We do not bow down to the threats of terrorism."

In the Sunday sunshine of Darling Harbour, most people seemed to agree. Many were attending multiple services in the city or surrounding suburbs, and those who weren't said long-distance travel or wrangling small children stopped them going to events, not fear.

No RSL sub-branch has cancelled or scaled back planned Anzac commemorations. Instead, the foiled plot had the effect of bringing Australians together, Rear Admiral Doolan said.

"I suspect that those who seek to disrupt us will in fact strengthen the resolve of Australians ... our determination to respect those who have done wonderful things for us in the past is far, far stronger than anything they can do," he said.

In response to the alleged plot, NSW Police issued a reminder to its officers to be aware of their personal safety when they entered and exited police stations, and reminded them to remain aware even when they are off duty, in line with the high national terrorism alert level.

"NSW Police enacted enhanced safety provisions in September last year and these remain in place," a spokesman said, adding the measures were being constantly reviewed.

"These enhanced provisions relate to access and security around police stations, the highest standards of personal security for officers, on and off duty, and ongoing intelligence gathering."

On Sunday, a Police Association official in Victoria urged members to avoid wearing even partial uniform when they weren't working, to avoid being identified and potentially becoming a target. Similar calls were made by some commanding officers in the Australian Defence Force to their juniors in September last year. NSW Police were unable to officially confirm if a similar practice existed for their officers.

A significant police presence is expected in central Sydney for events throughout Anzac Day, including mounted police and retired officers taking part in the CBD parade, but police say there's no need for concern.

"Australia's counterterrorism arrangements are well entrenched and regularly exercised to ensure they remain robust and relevant in the current threat environment."