New restrictions will come into effect in South Australia from Tuesday, capping guests at weddings, funerals and houses, and barring anyone – even state residents – coming in from Victoria.

Currently, South Australians are allowed to return home from Victoria but must quarantine for two weeks and be tested twice during that time.

Under the new rules, everyone else will be allowed in, though those coming from NSW and ACT will need to quarantine for two weeks and undergo the two tests during their isolation period.

There is no set date as to when that restriction will be lifted, Premier Steven Marshall confirmed on Friday.

South Australia has also capped weddings and funerals at 100 people and home gatherings at 50 people.

Only three cases of coronavirus have been recorded in the state this week, though that is a big jump for South Australia, which had only one other case recorded this month and only three in June.

Mr Marshall said all three of this week’s positive tests had come from Victoria.

The Premier said the outbreaks were “of great concern to us”.

“Most importantly of concern is the vast majority of the cases which have been identified in the last week are still under investigation,” he said.

“That means they don’t know the origin.”

A returned traveller in his 40s tested positive for coronavirus on Thursday, nearly two weeks after coming home from Victoria on July 9 and testing negative.

The man was in quarantine during his infectious period but has since been transferred to what SA chief health officer Dr Nicola Spurrier called a “medi-hotel arrangement” as a precaution.

In health advice released on Thursday, SA Health said outbreaks interstate – referring to those in Victoria and New South Wales – had caused a “significantly higher risk” of catching the virus.