NSW Premier Gladys Berejiklian has announced the border with South Australia will remain open.
It comes after a cluster of at least 17 COVID cases were detected in Adelaide.
Several states, including Western Australia, Tasmania and the Northern Territory, have announced that borders will close to SA.
Berejiklian said NSW authorities will be watching the situation in SA closely.
“The situation in South Australia is very concerning,” she said.
NSW recorded three COVID cases on Monday, two of which are in returned travellers in hotel quarantine.
The third case was an old infection.
“Investigations to date have not identified any further transmission from this case,” NSW Health said.