It has been 31 days since the last COVID-19 case was detected in the ACT and more than one week without any active infections.

Workers in high-risk settings such as hospitals and aged care have been told to avoid their workplace for 14-days if they have recently returned from greater Sydney or Newcastle, as NSW work to contain growing clusters.

The state reported 14 new cases in the 24 hours to 8pm Sunday.

That included one person in hotel quarantine and one case with no known source.

NSW Premier Gladys Berejiklian said the state was on high alert.

Residents have been told not to attend large gatherings and to minimise activity as much as possible.

"We are doing okay, we are holding the line but we are at least half way through a really critical phase," Ms Berejiklian said.

"It's important for people to be aware of where they've been and to assume every time they leave the house the people they've been in contact with have the virus."

Canberrans remain stranded at the Victorian border after NSW made a snap decision on Thursday to cancel their travel permits.

ACT Health confirmed 57,534 tests had been conducted to date.

There have been 113 cases in the ACT, including 110 people who have recovered and three deaths.