The change to apply from May 8 will allow for a full house of more than 50,000 fans at the next AFL showdown between Port Adelaide and the Adelaide Crows.

Some requirements for mask use will still apply, including on entry and exit and when buying food or using other facilities.

South Australia has also reported nine new coronavirus cases on Thursday, all in recent overseas arrivals.

Chief Public Health Officer Nicola Spurrier said that took the number of active infections in SA to 30, the highest number since the Parafield cluster of locally-acquired cases in November last year.

"Obviously, this puts me on edge and also members of my staff to make sure we are still protecting South Australians," she said.

"We need to make sure that all of our processes in our quarantine stream and our medi-hotels are as tight as possible."

She said officials were monitoring the capacity of the Tom's Court hotel facility in Adelaide, which is being used to house all returned travellers who test positive.

"We feel we're getting near capacity in terms of our concerns around safety," she said.

Professor Spurrier said discussions were already underway with the state and federal officials in regard to the number of overseas arrivals.

Port Adelaide Chief Executive Matthew Richardson said the increase in crowd numbers at Adelaide Oval was a fantastic outcome for local football fans.

"Our members have had to endure a lot in the last 12 months and have been so understanding of the situation," he said.

"The return to full capacity is a reward for them and all South Australians who have followed the COVID-19 protocols to ensure our state is in a good place."

Australian Associated Press