Thousands of protesters marched through Australia's capital to the parliament building on Saturday to decry COVID-19 vaccine mandates, the latest in a string of rallies against pandemic restrictions around the world.

Demonstrators packed Canberra's streets before massing outside the parliament, some waving the red Australian ensign flag associated with “sovereign citizens” who believe national laws do not apply to them.

Protesters, many with children, rallied under bright skies brandishing banners proclaiming “Fight for Your Freedom & Rights', "Free Aus Freedom Now", or "No forced drugs” written above a symbol of a syringe.

Police estimated there were up to 10,000 protesters. They were “generally well behaved”, a police spokesman said.

Three people were arrested including one man who drove his truck through a roadblock. Two others were taken into custody for a breach of the peace.

Australia says 94 percent of people aged over 16 have had at least two COVID-19 vaccinations.

Though getting the jab is voluntary, it is generally required for people entering the country and for those working in a range of professions deemed at particular risk such as caring for the elderly.

Some Australian states such as New South Wales have begun to relax proof-of-vaccine requirements for entry to pubs, restaurants or shops.

Prime Minister Scott Morrison, who must call a general election by mid-May, called on the protesters to act peacefully.

But the Australian leader also said he understood their concerns and stressed that the states — not the federal government — were responsible for many of the vaccine requirements.