Victoria has confirmed 20 days with no new virus cases or deaths, but authorities remain wary of a possible risk from South Australian visitors.

SA is in its first hours of a six-day lockdown – with even tougher rules than Victorians endured for months – to strike hard and early against an outbreak in Adelaide.

Despite SA residents have extremely limited permissible reasons for leaving home being extremely limited, Victorian Premier Daniel Andrews has asked people from his neighbouring state to cancel all non-essential interstate travel.

“Unless you have got an urgent reason, a really pressing reason to visit Victoria, now is not the time to come to Victoria,” he said on Wednesday.

On the road, Victoria has set up rapid coronavirus testing in the western town of Nhill for truck drivers crossing the SA border. More testing sites will follow on other busy trans-border routes within days.

Air travellers arriving in Melbourne or Mildura by plane from metropolitan Adelaide must undergo a coronavirus test, even if they don’t have symptoms.

Any truck driver who refuses to take a coronavirus test at the SA border will be sent back, while plane arrivals who refuse to be tested will be subject to public health orders requiring them to quarantine for 14 days.

Victoria has offered assistance to South Australia’s government, including lab capacity for coronavirus testing, Mr Andrews said.

Meanwhile, the Premier has flagged changes to Victoria’s mask rules as early as Sunday, following weeks of heated public debate.

“No one enjoys wearing a mask and no one enjoys them as the weather gets warmer,” he said.

He is also likely to announce a further easing of some of the state’s COVID rules.

There remain three active virus infections in Victoria, with 17,161 people tested in the previous 24 hours.

The state’s virus death toll stands at 819, with the national figure 907.

-with AAP