A transition committee meeting on Tuesday has ruled that travellers can cross the border from then but must isolate until they receive a negative virus test.

They will also be barred from attending any major events, including AFL matches.

People coming from regional Victoria will no longer be subject to any restrictions.

At the same time, SA has increased restrictions on travellers from Sydney as the cluster of coronavirus cases there increased to 21.

Travellers who have been in the City of Sydney, Randwick, Canada Bay and Woollahra in the past 14 days are required to self-isolate until they take a virus test, and must be retested on days 5 and 13.

Anyone who has been in the Waverley Council area is currently banned from entering SA.

The widening Sydney outbreak is casting doubt over the AFL game between the Sydney Swans and Port Adelaide, scheduled at Adelaide Oval on Saturday.

Premier Steven Marshall said previously that SA Health was liaising with the AFL and he was hopeful it would proceed, most likely subject to the same strict rules on the visiting team as those imposed on Melbourne clubs recently.

That includes having the players fly in and out on the same day on a charter plane, restricting the size of the group who must all return a negative test before arriving and also requiring a declaration that they have not visited any coronavirus exposure sites.

"We don't want to go backwards by bringing COVID-19 into South Australia. So we do take a prudent position on this," Mr Marshall said.

Australian Associated Press