An international arrival isolating in a South Australian medi-hotel has defied his quarantine requirements after he spent about eight hours in the community in the middle of the night.

The man, who landed in Adelaide on August 3, was completing the mandatory 14 days of quarantine in the Hotel Grand Chancellor in Adelaide’s CBD.

But SA Police claimed the international arrival “deliberately” left the facility just after 10pm on Thursday night.

After spending about eight hours within the community, the man voluntarily returned to the medi-hotel at about 6am on Friday.

Authorities reassured the community there was no risk posed from the man at that time because he was not infectious with Covid-19.

He returned negative results on his day one, five and nine tests and was again tested on Friday. It also came back negative.

Police Commissioner and state co-ordinator Grant Stevens reiterated that South Australians should not be alarmed by the incident.

But he said this was the first time such a breach had happened in the state since the medi-hotel program began.

There have so far been about 22,000 guests that have isolated in a South Australian medi-hotel.

“It is disappointing that despite our robust security arrangements for our medi-hotels, this breach of security occurred,” Mr Stevens said.

“We will continue to work to maintain the high standard of security in our medi-hotels and will implement any identified changes to restrict future similar breaches of security.”

A senior police officer will investigate the circumstances of the security breach, with an outcome expected to be completed in the coming days.

Further action against the man will also be addressed as a part of the investigation.

Under South Australian law, any individual person who breaches Covid-19 directions faces a $1000 fine, while businesses could be slapped with a $5000 infringement.