The RSL has condemned anti-monarchy protesters who destroyed the Australian flag at rallies as deplorable.
Protesters at Birrarung Marr, an inner-city park by the Yarra River, cut up the flag on Thursday while chanting "abolish the monarchy", while in the Sydney CBD the flag was burnt.
National RSL president Greg Melick said the protesters had demonstrated a gross level of disrespect that would be denounced by all reasonable Australians.
"Both Her Majesty and our national flag are entitled to and deserve the deepest respect," Mr Melick said.
"The protesters' actions yesterday were deplorable and dishonoured Australian service men and women who have made the ultimate sacrifice for our nation."
The Melbourne rally, led by federal Greens senator Lidia Thorpe, was one of the largest on the Queen's National Day of Mourning.
Ms Thorpe's hands were covered in fake blood as she spoke to the crowd about the countless atrocities and human rights violations against First Nations peoples.
Mr Melick said he was severely disappointed by the actions of Ms Thorpe who chose to lead a rally instead of honouring the Queen at the memorial service in Canberra.