MELBOURNE: The Australian Open tennis tournament will proceed without crowds over the next five days after the state of Victoria was placed under a snap lockdown from midnight on Friday to contain a fresh outbreak of COVID-19.

State Premier Daniel Andrews announced the measures after the highly transmissable strain of COVID-19 linked to Britain infected 13 people.

"Australian Open sessions today and tonight will continue as planned with COVID safe protocols in place," organisers Tennis Australia said in a statement.

"We are notifying ticket holders, players and staff that there will be no fans onsite at the Australian Open for five days, commencing from Saturday."

Fans who had already bought tickets would get a refund.Andrews said the Australian Open would be treated like any other professional sporting event in the state.

"Large and small professional sport events ... will function essentially as a workplace," he told reporters in Melbourne.

"But they will not function as an entertainment event, because there will be no crowds."

The tournament, one of the sport's four Grand Slams, was delayed by three weeks and only went ahead after more than a 1,000 players and support staff underwent 14 days of quarantine.

One day's play in the warm-up tournaments at Melbourne Park was called off last week after a worker at one of the tennis quarantine hotels tested positive for COVID-19. All the players underwent testing and were cleared of infection.

Crowds at Melbourne Park were capped at 30,000 per day at the start of the tournament -- around 50% of the usual attendance -- but only 21,000 came through the gates on Thursday.

Organisers would have been hoping for bumper crowds on Saturday and Sunday as the first weekend of the tournament usually attracts the most visitors to Melbourne Park.