NZ health authorities are considering their response after learning of the positive test, which may snap the country’s long streak of over 100 days without community transmission.

The person travelled to NZ last weekend, leaving Sydney on Friday night and heading back on Monday.

The most likely scenario – based on testing and the person’s symptoms – is he caught the virus in Australia and travelled to NZ while contagious.

Genomic testing will show whether the case is linked to the current Bondi outbreak.

Director General of Health Ashley Bloomfield said officials were considering all responses, including a snap lockdown, saying “everything’s on the table”.

“It’s proven useful in the past for us to not rule anything out,” he told Radio NZ.

“We will be looking at whether other measures might be required. Wider use of masks, restrictions on gatherings size for a period.”

Four close contacts have already been identified.

Wellington locations of interest have been revealed, including the national museum – Te Papa – and sports bar Jack Hackett.

NSW Health has issued an alert for passengers travelling on Qantas flight QF163 on Friday night to Wellington and anyone who flew on Monday morning on Air New Zealand flight NZ247 from Wellington to Sydney.

New Zealand health authorities closed the trans-Tasman bubble with NSW for at least 72 hours after the state recorded 10 new cases on Tuesday, lifting the so-called Bondi COVID-19 cluster to 21.

Other Australian states have imposed border restrictions for people from Sydney’s hotspot areas with Victoria declaring seven Sydney local government areas “red zones”.

Non-Victorian residents who have been in the City of Sydney, Waverley, Woollahra, Bayside, Canada Bay, Inner West and Randwick council areas are not allowed to enter Victoria.

Mandatory mask rules have been extended by a week in Sydney, QR codes are set to become mandatory in all NSW shops and there’s heightened anxiety Sydney could be heading for a lockdown.

Premier Gladys Berejiklian did not rule this out but said she had a “degree of confidence” because there was only one infection not linked to a known case.

“If we suddenly have a number of unlinked cases and if we suddenly have them outside the geographic region they are concentrated in, that will obviously adjust the health advice and we will respond to that,” she said on Tuesday.

Seven of the 10 new locally acquired Sydney cases of COVID-19 flagged on Tuesday had missed the 8pm reporting deadline on Monday and will be counted for the following 24-hour period, which will be announced on Wednesday.

They included six household contacts of previous cases who have been in isolation and a child in Sydney’s east.

Berejiklian expects household contacts who were already in isolation to test positive.

All of the new cases, except for two, were already in isolation when tested and all of the cases except for one – a student at St Charles Catholic Primary School in Waverley – were linked to existing cases.

On Tuesday night, new COVID-19 exposure sites were announced for Sydney’s CBD and east, including the popular Totti’s restaurant in Bondi, The Royal Bondi pub and a Woolworths at Spring Farm in Sydney’s southwest.

NSW Health also ramped up its advice around the original infection site at Westfield Bondi Junction and is asking anyone who was there – including the car park area – at any time between June 12 and 18 June to get tested.

Masks were now compulsory until midnight on June 30 on public transport and in most indoor settings for people in Greater Sydney, The Blue Mountains, the Illawarra and Shellharbour regions.