Health authorities in New South Wales have reported 11 new coronavirus infections, with the source of one mystery case in Western Sydney a concern.

Of the new cases, nine were locally acquired from known cases, including one person who attended the Apollo restaurant in Potts Point.

One case is under investigation — a woman in her 60s from south-western Sydney.

The other case was acquired in Victoria and that person has been self-isolating.

NSW Deputy Chief Health Officer Jeremy McAnulty reiterated the four-pronged approach to tackling coronavirus, with people being asked to stay home, maintain social-distancing and good hand hygiene, and wear a mask where social distancing wasn’t possible.

“While most cases in the past week have been associated with local clusters and close contacts with known cases, some have not been linked to known cases,” Dr McAnulty said.

A total of 27,937 people were tested in NSW in the 24 hours to 8:00pm Thursday.

There have now been 3,653 cases of coronavirus in NSW since the pandemic began.

NSW Health is treating 109 people for the virus, with 10 in intensive care and five on ventilators.

Elsewhere, a household contact of a previously reported case attended St Francis Xavier’s College in Hamilton East, Newcastle, on Monday, Tuesday and Wednesday this week.

The school is now closed for cleaning and contact tracing is underway.

A 31-year-old woman has been fined $1,000 and ordered to return to Victoria after crossing the border at a checkpoint in Albury.

Checks found she was not at the Nimbin address she had given for her 14-day isolation period.

In an unrelated incident, a 50-year-old woman playing a poker machine in an Albury pub was found to have a cross-border travel permit for work only.

She was fined $1,000 and ordered to return to Victoria.