SYDNEY (Reuters) – Australian authorities are taking legal action to try stop a Black Lives Matter protest scheduled to take place in Sydney on Saturday, citing the risk of an outbreak of COVID-19 given the large numbers expected to attend.

The last-minute move by the New South Wales state government on Friday came after Prime Minister Scott Morrison told people not to attend the gathering and similar rallies in Melbourne and other major cities.

NSW police had originally approved the protest, on the understanding there would be fewer than 500 participants. Organizers now expect thousands of people to attend the gatherings.

“The New South Wales government would never, ever give the green light to thousands of people flagrantly disregarding the health orders,” NSW Premier Gladys Berejiklian told reporters in Sydney.

The NSW Supreme Court will hear the matter on Friday afternoon.

Morrison said earlier that people should find other ways to express anger following the death of black American George Floyd in U.S. police custody.

“The health advice is very clear, it’s not a good idea to go,” he told reporters in Canberra. “Let’s find a better way and another way to express these sentiments … let’s exercise our liberties responsibly.”

The Melbourne protest is still scheduled to take place with state police approval, although Victoria state Premier Daniel Andrews has urged people not to attend.

The protests will also throw a spotlight on police treatment of Australian indigenous people, including the deaths of Aboriginal men in custody.

Australia has reported daily single digit and low double digit numbers of new COVID-19 cases in recent weeks and has 490 active cases, with just 25 people in hospital.