Opposition Leader Angus Taylor on Sunday denied the proposal was aimed at warding off the threat of right-wing rival One Nation, which has soared above the coalition in the polls.
"We need to stand up for Australia," he told News24's Sunday Agenda program.
Serious public desecration of the Australian flag, designed to incite hatred, would be a criminal offence punishable by a year in jail under the policy.
Those who deface, desecrate or destroy public war memorials would also face serious penalties under a new federal criminal offence.
Any criminal offences for such defacement are currently implemented under a patchwork of state and territory laws.
The policy would extend to damage to significant memorials commemorating Australia's history, like statues of Captain Cook.
Under the coalition's proposal, January 26 would also be enshrined as Australia's national day, requiring future changes to be put to a plebiscite.
The defacing of memorials and the national flag is governed by state and territory laws, all with different penalties.
It is at least the eighth federal attempt in Australia's history for burning of the flag to be made illegal, all of which have previously failed.
Concerns have previously been raised about whether such a measure would stand up to a constitutional challenge.
Long-standing Liberal prime minister John Howard also opposed the measure, saying in 2006 that criminalising flag-burning would "only turn yahoo behaviour into martyrdom".
But Mr Taylor insisted it was an important policy for protecting Australia's way of life, repeatedly denying the timing was due to One Nation's renewed appeal with voters.
"What I make of the situation right now is we've got to re-establish trust with the Australian people," he said.
"When I get out and talk to people, there are a lot of Australians who want us to go back to those core Liberal and National Party values."
One Nation has previously advocated for the same policy.
Labor assistant minister Matt Thistlethwaite said the plan to criminalise flag-burning was alarmist and would restrict freedom of speech.
"I think that there's a bit of an element of desperation there, trying to chase One Nation and further to the right and to capture some of those votes," he said.
When asked if there were any circumstances in which the Liberals and Nationals would enter a coalition with One Nation to form government, Mr Taylor said: "No."
His comments come from conflicting answers from other coalition figures, some of whom left the door open to a possible future partnership.
The Liberals and Nationals have consistently lost ground to One Nation since the coalition's bruising 2025 election loss.
The latest Newspoll put One Nation's primary vote at 30 per cent, ahead of Labor's 29 per cent and the coalition's 19 per cent.
8°C