The Australian state of Victoria will enter lockdown for a third time in a bid to suppress an outbreak of the UK strain of coronavirus. Officials this week found 13 cases stemming from a quarantine worker who became infected at a Melbourne hotel.

With the lockdown beginning, the government has said the Australian Open tennis tournament would continue in the state's capital, Melbourne. Spectators will be banned from attending the event, which had previously allowed up to 30,000 visitors a day. Tickets will be refunded, tournament director Craig Tiley said.

Victorian Premier Daniel Andrews said the current outbreak was not linked to the quarantine hotels used by the tennis players. He stressed that a "circuit breaker" was needed to combat the "hyper-infectious" strain which he said had likely already seeded other infections in the community.

"This is the fastest-moving, most infectious strain of coronavirus that we have seen," he said, adding that almost 1,000 close contacts had already been reached. Prior to this outbreak, Victoria had not seen a local infection for 28 days and the state had largely eliminated the virus.

Many Melbourne residents have expressed dismay but also resignation over the retreat into lockdown again. Last year, in Australia's winter, the city endured one of the world's longest and strictest lockdowns to overcome a second wave which led to more than 90% of Australia's 29,000 cases and 909 deaths.

"We've built something precious, and we have to make difficult decisions, and do difficult things, in order to defend what we've built," Mr Andrews said. "I am confident that this short, sharp circuit breaker will be effective. We will be able to smother this."

The state will be under the following restrictions for five days:

·         People must stay at home except for shopping, exercise, caregiving and essential work needs

·         No gatherings allowed

·         Travel is restricted to within 5km (3.1 miles) of the home

·         Mask wearing is mandatory in public

·         Places of worship and all non-essential venues are closed

·         Schools are closed except for children of essential workers

Meanwhile, South Australia, Queensland and Western Australia have announced travel bans on people from Melbourne. Further border closures are expected. International flights to Melbourne will also be cancelled, authorities said.