The president of Austinmer Thirroul RSL Sub-Branch, Will Lee, was "absolutely devastated" this morning when he discovered that the wooden soldier's rifle atop Thirroul's World War I statue at Woodward Memorial Park had been stolen.

"I was down there this morning," Will said, "and we because we've had a couple of our members who've passed away in the last few months, I was there taking the tape off the stainless-steel plaques that we put on there, and just looked up and the rifle wasn't there."

Will doesn't know when the vandalism took place, as he last visited the memorial in August, but it would have taken a determined effort to remove the rifle, he said. "For someone to actually climb up there and take it off – it'd be a feat to do that."

The memorial honours local members of the Australian Defence Force, including those who fought and died in World War I.

It was erected on the corner of Lawrence Hargrave Drive and Railway Parade in 1919 and is considered the oldest First World War monument in the Illawarra, Will told the Illawarra Flame.

Its foundation stone was laid on 18 October 1919 by Mrs Arnold Higgins and the official unveiling was performed by Mrs "Grannie" Riach on Anzac Day, 25 April 1920.

This is not the first time that the rifle has been targeted by vandals.

"About five years ago, someone else climbed up there and broke half of it off," Will said. "So the [Wollongong City Council] insurance paid for a brand-new .303 rifle to be made out of wood – exactly to the specifications what it would have been.

"And now, someone's actually gone up there and taken the whole thing."

Will has reported the missing rifle to NSW Police and Wollongong City Council. He recommends anyone with more information should call Crime Stoppers on 1800 333 000.