South Australia has reported three new cases of COVID-19, all returned travellers who are in hotel quarantine.

SA Health says the three women, aged in their 20s, 30s and 60s, were all on the same overseas flight and were found to be infected on their day one tests.

Their cases take the total number of infections in SA since the start of the pandemic to 479 with six of those still active.

All of the active cases remain in quarantine and none are considered a threat to the wider community.

So far this year, SA has conducted more than 504,500 coronavirus tests.

AAP