By Renju Jose
SYDNEY (Reuters) -Australia's most populous state on Tuesday reported its biggest daily increase in COVID-19 cases in nearly a week and extended the wearing of masks inside buildings, while New Zealand paused quarantine-free travel with the state.
Ten new locally-acquired cases were reported in New South Wales state as officials fight to contain a cluster of the highly infectious Delta virus variant. Eight of the 10 were household contacts of previous cases in isolation.
"Given how absolutely contagious the virus is, we expected household contacts already in isolation were likely to get the virus," state Premier Gladys Berejiklian told reporters in Sydney.
Masks will be mandatory indoors in Sydney, home to a fifth of Australia's 25 million population, for another week from Thursday morning although officials stopped short of imposing further curbs as the cluster increased to 21 infections in six days.
New Zealand, which in April began letting visitors from Australia enter the country without undergoing hotel quarantine, said it was pausing the "travel bubble" for three days for people flying from NSW. The most popular flight between the countries is between Sydney and Auckland.
The Delta variant, which has been classified by the World Health Organization (WHO) as among the four COVID-19 variants of concern, most likely caused the latest devastating outbreak in India.
Authorities in New South Wales say the first infections in the state in more than a month are linked to a driver who transports overseas airline crew and who visited several places, including a shopping centre in Bondi, a popular tourist hotspot.
Neighbouring Victoria state, which emerged from a strict COVID-19 lockdown more than a week ago, reported no local cases on Tuesday, prompting New Zealand to restart its quarantine-free travel with the state from Tuesday night.
Victoria's low number of cases during the last week has also encouraged the states of South Australia, Tasmania, Queensland and the Northern Territory to begin easing border restrictions.
Strict border controls, swift tracing systems, tough social distancing rules and high community compliance have kept Australia's COVID-19 numbers relatively low, with just over 30,350 cases and 910 deaths.
Australia closed its borders to all but citizens and permanent residents in March 2020 and overseas travellers must undergo two weeks of mandatory hotel quarantine on their return.
Australian team's medical director for the Tokyo Olympics David Hughes said on Tuesday monitoring infection rates among fully vaccinated Australian athletes and officials returning from the Olympics could help inform future travel policy.