SYDNEY (REUTERS) - Australian researchers said on Thursday (April 16) they expect to roll out wide testing of raw sewage for the presence of the new coronavirus within weeks to help pinpoint communities at risk, after a successful regional pilot.

The trial in Queensland by national science agency Csiro and the University of Queensland will be used to develop a surveillance system researchers said will help officials when they start to wind back restrictions on public movement.

The new project utilises an existing system under which crime agencies monitor wastewater, covering about 57 per cent of the population, to detect the presence of illicit drugs in Australian cities.

In the Queensland trial, scientists were able to detect a gene fragment of the coronavirus in untreated sewage from two wastewater treatment plants.

Used on a wider scale, sewage sampling would be able to detect the approximate number of people infected in a geographic area without testing every individual, the Csiro said. Officials are currently testing thousands of Australians daily using conventional tests.

The Csiro's land and water science director, Dr Paul Bertsch, said the project would help governments ease nationwide curbs on public movement by highlighting problem areas, allowing many Australians to get out of their homes.

"I see it as an important surveillance tool for easing restrictions," Dr Bertsch told Reuters. "As governments ease up, they will need to keep monitoring and respond to outbreaks."

Australia has closed restaurants, bars and stores deemed "non-essential" while using the threat of fines and even prison to stop public gatherings of more than two people in a bid to slow transmission of the flu-like illness.

The strict measures have helped slow growth in the daily rate of new infections drastically to low single digits, from about 25 per cent several weeks ago, for a total of about 6,500 infections, including 63 deaths.

Prime Minister Scott Morrison said on Thursday those restrictions would stay in place for at least another month, although officials have begun talking about how to start a wind-back.

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Health Minister Greg Hunt said a wider detection regimen, including sewage sampling, would help show whether there were Covid-19 cases in the broader community.

University of Queensland Professor Kevin Thomas, one of the researchers on the sewage trial, said it was likely national testing would be achieved "in a matter of weeks".

Remote and regional communities, where it is more difficult for the health authorities to conduct traditional swab tests, could particularly stand to benefit, he said.

Dr Bertsch said sewage sampling could be conducted daily, and while the first tests would be taken at wastewater treatment plants, there was potential to take sampling "further up the pipe" to a suburb level by going down neighbourhood man-holes.

Dr Bertsch said Chinese data showed the virus could be detected in faeces within three days, quicker than many cases were being detected with conventional tests.