South Australian Premier Steven Marshall is furious at the "disgraceful conduct" of a pizza worker who claims he sparked the state's lockdown.

Marshall said that one of the close contacts from Woodville Pizza Bar had "deliberately misled" contact tracers.

“Their story didn’t add up. We pursued them. We now know that they lied. I stress this point, that this is still a very dangerous cluster and our expert health – our health experts remain extremely concerned,” he said.

“I will not let the disgraceful conduct of a single individual to keep SA in these circuit breaker conditions one day longer than what is necessary. However, this lie still means that our contact tracers need breathing space to contact people but not for as long.”

Despite putting the state into a sudden lockdown, the man will not be charged or penalised for withholding information, according to Police Commissioner Grant Stevens.

He's urged angry South Australians to look towards Christmas instead.

"I understand the community sentiment about the actions of this person. I don't think there will be a single person who is not going to be, for some reason, affected or upset by the fact we have had to go into such a strict lockdown," he said.

"My expectations of the community are that we act as we have with every other challenge that we have faced through COVID-19.

"There is a genuine basis for people to be outraged but we need to move past this, keep doing what we are doing so we crush this particular cluster and get back to where we were before 15 November and aim for December 1 where we see ourselves getting ready for Christmas and spending time with families."

The state needs to stay in lockdown for one more day due to the actions of the person who initially lied.

Stevens outlined the consequences to news.com.au.

"The first consequence from this lie is we went into a six-day lockdown," he said.

"The second consequence is this person's failure to be truthful with contact tracers means his close associates, who we understand he's had close contact with, haven't been identified and are currently in the community.

"We need to lock that up before we move into a lower level of restrictions. Our goal is to do that by midnight Saturday."

The state is currently managing 44 suspected cases of coronavirus, with 4,500 people in isolation.

This is due to the state initially moving so quickly, according to SA's chief public health officer Professor Nicola Spurrier.

"I just want to give people a little warning we are expecting to see the number of cases here in South Australia rising over the next couple of days," she said.

"That is because we moved so early in the beginning of this cluster, and put people in quarantine, and when we first tested them, they had not actually become positive.

"But we will be expecting that to happen now over the next couple of days."

"That is that double ring, directly linked to this cluster, in quarantine, and they will not be able to come out of that on Saturday night, they have their 14 days of quarantine," Prof Spurrier said.