INTERNATIONAL: Three people have been arrested after a crowd of up to 10,000 anti-vaccine protesters gathered outside Parliament House in Canberra today.

The protesters, who are largely marching against vaccine mandates but also include members of a wide range of different protest groups, had earlier forced the cancellation of a popular book fair in Canberra to raise money for mental health.

"Overnight, a significant influx of people to EPIC saw fences moved and campers established in non-camping areas," an ACT Police spokesperson told reporters.

Thousands of demonstrators have been camping at the Exhibition Park in Canberra (EPIC) without authorisation.

The campers have been ordered to move on from Exhibition Park on Sunday to prepare the venue for the Royal Canberra Show.

"People who remain in EPIC after this time may be considered trespassing," ACT Police said in a statement yesterday.

The vast majority of protesters are not actually from Canberra — the ACT is the most vaccinated jurisdiction in Australia, with more than 99 per cent of the population aged over 16 have had a second dose.