A number of monuments across Sydney's CBD have been attacked by vandals, including a statue of Captain James Cook, following fierce public debate about whether it should be changed.
Police are searching for a man, captured on security cameras walking alone through the city in the middle of the night.
The words "change the date" and "no pride in genocide" were spray-painted on the statue of Captain Cook, with similar words scrawled on that of Lachlan Macquarie and Queen Victoria.
The slogans allude to a growing public debate about the way the European arrival in Australia is commemorated.
Police believe the statues were vandalised between 2.25am and 3.15am on Saturday.
They released CCTV images on Saturday that depict a man of Caucasian appearance with a beard and wearing black sunglasses, a khaki coloured jacket with a red shirt or scarf underneath, black track pants and brown boots.
Graffiti was also sprayed on the Archibald Memorial Fountain, ANZAC Memorial, several park benches in Hyde Park, and in Martin Place.
The graffiti attack comes just days after indigenous broadcaster Stan Grant called for the inscription on the Cook statue - saying he "discovered" the territory in 1770 - be changed.
But Grant has described the attack as "appalling" and "vandalism".
"If we can't have this conversation in a country, democratically and respectfully, then it is just disgraceful," Grant told Fairfax Media on Saturday.
Malcolm Turnbull, weighing into the debate on Friday, said Grant was "dead wrong" about altering the monuments.
The prime minister said the vast majority of Australians would share his horror at the thought of "rewriting history" by editing the inscriptions on statues.
"All of those statues, all of those monuments, are part of our history and we should respect them and preserve them," he told 3AW radio.
"By all means, put up other monuments, put up other signs and sites that explain our history."
He denounced such a "Stalinist exercise" of trying to white out or obliterate parts of Australia's history.
"You don't rewrite history by editing stuff out. If you want to write a new chapter of our history, if you want to challenge assumptions in the past, by all means do so," he said.
A City of Sydney spokeswoman said the council was also cleaning up graffiti that appeared overnight in Martin Place and Macquarie Street.
"NSW Police have completed forensic work and City cleaning crews have commenced work to remove the unlawful graffiti," she told AAP