South Australia is moving to an online system for access to the state as its level of coronavirus restrictions is reduced to its lowest level since March.

South Australia is moving to a pre-approval process for all people entering the state as part of ongoing COVID-19 restrictions.

From Wednesday anyone wanting to come to SA by road or air will need to apply through an online form, a process officials say will speed up access at the state's borders.

Anyone arriving from Queensland, Western Australia, Tasmania and the Northern Territory will not be required to quarantine, but 14 days of isolation will continue for anyone from NSW, Victoria and the ACT.

SA is due to lift quarantine requirements on those jurisdictions on July 20, but Police Commissioner Grant Stevens says the spike in cases in Victoria is being monitored and could impact on that schedule.

Victoria reported 75 new cases on Monday after revealing 90 new infections over the weekend.

"We'll take advice from the experts in SA Health in relation to the efforts in Victoria to contain the virus and to properly establish the extent of the spread into the Victorian community," Mr Stevens said.

"The reality is, the numbers we're seeing today relate to activities that occurred over the last two weeks, so we may see a much better performance from Victoria over the next few days.

"It's important to everybody that Victoria gets this under control."

As well as impending border changes, SA moved to level three of lifting wider coronavirus measures on Monday, relaxing density requirements for pubs, bars and restaurants - with one person allowed for every two square metres.

Large venues such as Adelaide Oval will be free to cater for up to 50 per cent of their normal capacity, provided health officials have approved their COVID-19 safety plans.

The Adelaide Casino will also reopen along with the Monarto open range zoo.

Premier Steven Marshall says the changes allow more businesses to open and employ more people.

"But it's not a time to get complacent. It's up to all of us to heed the health messages," he said.

"If you're sick, stay home. If you have cold and flu symptoms, get tested. And keep up good hygiene practices."

SA reported no new coronavirus cases on Sunday, taking the state's run of days without a new infection to more than a month.

However, 250 repatriated Australians arrived in Adelaide from India on Saturday and local health officials have warned that could result in some new cases.