There were also five positive coronavirus cases among overseas travellers in hotel quarantine from the 7391 people tested in the 24 hours to 8pm on Sunday night, compared with 12,823 the previous day.

NSW Deputy Chief Health Officer Jeremy McAnulty said the new locally acquired case was a household contact of a case reported on Sunday, which was linked to another two previously reported cases. The source still being investigated.

"The testing numbers are much lower than we would like," he said on Monday.

NSW Health was still working to contain a cluster of eight linked to a private clinic in Liverpool, as well as other clusters in west and southwest Sydney with patients of a Lakemba clinic warned to monitor for symptoms.

People in those areas have again been urged to get tested even if they have mild symptoms like a runny nose or scratchy throat, cough, fever or others that could be COVID-19.

Meanwhile NSW Labor has renewed calls for the government to mandate mask-wearing on public transport after passengers on a Sydney bus on the long weekend were urged to get tested and remain isolated for 14 days regardless of their test result.

People who were on a bus that left Central station just before midnight on October 4 and arrived at Strathfield at 12.15am on October 5, were now considered close contacts of an infected passenger.

Opposition leader Jodi McKay has for months been calling on the government to make masks mandatory.

"If (Transport Minister) Andrew Constance says he's worried about complacency then maybe he should take a good look at his own lack of action. The buck stops with him and the Premier," she tweeted on Monday.

A Transport for NSW spokesperson said the department continued to follow the advice of NSW Health by strongly recommending the use of face masks on public transport.

There are 54 people being treated in hospitals for COVID-19 but only one is in intensive care.

Australian Associated Press