According to information provided by the Australian Capital Territory (ACT) government, the virus "was found in a sewage sample collected on January 27 from the Belconnen wastewater testing location", reports Xinhua news agency.

Vanessa Johnston, deputy chief health officer of the ACT, said that the detection does not mean the Capital Territory has new Covid-19 cases, but it was treated with caution.

"It may represent a person who has recovered from Covid-19 and is no longer infectious but is continuing to shed the virus," Johnston said.

She said that the shedding can last for weeks after the person recovered.

"This detection may be indicative of a person in this category, who has recently returned home or visited the ACT," she said.

"For example, we know that ACT residents continue to return to Australia from overseas. These individuals undergo hotel quarantine in other states and territories before returning to the ACT. Some of these residents develop Covid-19 in hotel quarantine and then return to the ACT once they have recovered and are no longer infectious.

"However, it may also be an undetected active case, which is why the community should remain alert, but not alarmed," the top health official added.

The ACT government urged people with even the mildest of symptoms to get tested for Covid-19.

"We urge anyone who lives in, works in, or has recently visited the Belconnen area, to get tested for Covid-19 if they are experiencing even the mildest of symptoms, and to self-isolate until they receive a negative result. This is particularly important for anyone who has recently travelled outside the ACT," said Johnston.

"If there is an active case we are unaware of, it is vital that we detect this quickly to keep the community safe."

Sewage was tested for fragments of the virus that causes Covid-19 at six locations in the ACT weekly.

The ACT has so far recorded 118 coronavirus cases, with three deaths.