Casula's Crossroads Hotel has been linked to new COVID-19 infections that have increased the number of active cases in NSW.

The ACT government on Sunday said the pub was a site of a concerning new cluster of cases and urged anyone who visited the hotel between July 3-10 to isolate immediately and contact ACT Health.

No new cases were reported by ACT health authorities on Sunday but chief health officer Dr Kerryn Coleman urged vigilance from the territory.

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She said the ACT's quarantine period for Canberrans returning from Victoria was critical to preventing the territory from having the community transmission now driving up the state's new COVID-19 infections.

Canberrans who had been in Victoria within the past 14 days must notify ACT Health before returning to the territory, Dr Coleman said.

"We will work with you to understand what quarantine requirements you might have, including how long you need to quarantine for and what services exist that may help you during this period," she said.

"Given the amount of community transmission in parts of Victoria, this quarantine period is critical in preventing the same situation from unfolding here in the ACT.

"If you have been in Victoria in the past 14 days and entered the ACT prior to the quarantine directions being issued, I urge you to stay at home for 14 days from leaving Victoria and remain extremely vigilant for symptoms."

Dr Coleman has warned more coronavirus cases are likely in the coming weeks. There are now five active cases in the ACT, all recorded last week after a month free of the coronavirus. The cases are linked to the Victorian outbreak. Four are from a Gungahlin household and the fifth was a close contact of a member of that household.

The ACT has recorded more than 36,500 negative tests.