Days-long rallies against Covid-19 vaccination mandates picked up in numbers in New Zealand and Australia on Saturday, with protesters blocking roads and disrupting life in the countries' capitals.

About 10,000 protesters gathered at Canberra's major showgrounds, forcing the cancellation of a popular charity book fair, bringing traffic to a standstill and blocking roads in the Australian capital.

Police said three people were arrested, but overall the crowd was "well behaved".

In New Zealand's Wellington, hundreds of demonstrators gathered near the distinctive "Beehive" parliament for a fifth day despite drenching rain.

Inspired by truckers' demonstrations in Canada, the protesters have occupied and blocked several streets around parliament with their trucks, vans and motorcycles.

Protests remain relatively small in highly vaccinated New Zealand and Australia, where overwhelming majority of the population supports inoculations. However, the movement has persevered, with rallies occasionally turning violent.

Australia Prime Minister Scott Morrison said demonstrators had a right to protest, asking them to do it in a peaceful and respectful way.

He noted most vaccination mandates have been imposed by the states and territories, not the federal government.

"So, I understand their concerns about these issues," Morrison, who has been urging vaccinations, told reporters in Sydney.

The federal government mandated last year vaccinations for aged care workers, disability workers and those that are working in high-risk situations in health system. Most states and territories have imposed broader mandates and barred those not vaccinated from restaurants, concerts and many public venues.

Australian Opposition Leader Anthony Albanese, speaking at a media conference in Sydney, said the rallies were not going to gain widespread support. "Go home," he told the demonstrators.

New Zealand media footage showed one person being stretchered from the rally, carried by paramedics and police. No arrest had been made as of late Saturday, according to the police, who arrested more than 100 people on Thursday.

New Zealand logged a daily record of 454 community Covid-19 cases on Saturday.

A country of five million people, New Zealand has reported just under 19,000 confirmed cases and 53 deaths since the pandemic began. About 94% of eligible people are vaccinated, with shots mandatory for some staff in frontline jobs.

In Australia, which is opening its borders to tourists later this month, 94% of those aged 16 and over are double-vaccinated, but the country is still battling a wave of the highly transmissible Omicron variant.

There were at least 65 coronavirus-deaths reported across Australia on Saturday.