A police boat patrols the river bordering the Southbank precinct in Brisbane. Photo: AFP/Willaim West

Australia’s third-largest city was headed into another lockdown Friday and nationwide restrictions on international arrivals were being tightened after a cleaner at a quarantine hotel contracted the highly infectious UK strain of Covid-19.

More than two million residents in the Greater Brisbane area will have to stay at home for at least three days from Friday evening, authorities said.

“If we are going to stop the spread of this infectious strain, this UK strain, we must act immediately,” Queensland Premier Annastacia Palaszczuk told the media.

Large queues formed at shops around the city, with officials urging people to stop panic-buying. The incoming restrictions will still allow residents to leave home to buy essentials.

On Brisbane’s central shopping strip, Queen Street Mall, people voiced their support for the measures – keen to avoid the soaring case numbers seen as the variant takes hold in Britain.

Andy McPhee, 51, a Brisbane resident who works for an international firm, said the lockdown paled in comparison to what his colleagues overseas were experiencing.

“I don’t think a three-day lockdown is going to hurt us at all. I think it’s imperative to stamp out the virus,” said McPhee.

“One case becomes two and two cases become 10 so before you know it, it can get a bit out of control.”

The variant, which first triggered warnings in the UK last month, appears to be more infectious than Covid-19 strains previously detected in Australia.

Several UK and South African variant cases have been detected in travelers now under mandatory quarantine in recent weeks.

But the Queensland case was the first to be contracted locally and is believed to have spread to a cleaner from a returning traveler isolating in a Brisbane quarantine hotel.

The city’s lockdown signaled a return of restrictions unseen there since March, with residents ordered to stay home and told to wear masks when leaving for essential reasons only.

Following the announcement, authorities around the country restricted travel to and from Brisbane and further tightened rules on international arrivals.

Prime Minister Scott Morrison said all international travelers would now be required to undergo testing before flying to Australia.

The already low number of arrivals would also be temporarily reduced by 50%.

“There are many unknowns and uncertainties in relation to the new strain, and so that’s why this precautionary approach, we believe, is very sensible,” Morrison said.

The state of Queensland recorded no new cases of community transmission on Friday.

Before the announcement, Brisbane was among several Australian cities enjoying a return to relative normality during the southern hemisphere’s summer.

But recent outbreaks in Sydney and Melbourne had forced travel across state borders to be tightly restricted again amid mounting pressure on officials to hasten the vaccine’s rollout.

On Thursday, Morrison announced plans to bring forward the planned vaccine rollouts by weeks. They are now slated to begin in February.

Australia has recorded more than 28,500 Covid-19 cases and 909 deaths linked to the virus, in a population of about 25 million.