New Zealand will lift its partial suspension of a "travel bubble" with Australia from midnight on Sunday as fears of a COVID-19 outbreak in Sydney eased.

New Zealand had blocked travel to and from New South Wales, Australia's most populous state, on Thursday after a couple in Sydney with no links to high risk professions or people tested positive for COVID-19.

The cases prompted a reinstatement of some social distancing measures around Sydney, and a campaign to get more people tested, as authorities scrambled to determine the source of infection.  

However, state health officials on Saturday reported a second straight day without a new case, allaying concerns about a wider outbreak in the city.

New Zealand COVID-19 Response Minister Chris Hipkins said travel to and from NSW, home to one-third of Australia's 25 million population, would resume after health officials determined the risk to New Zealand was low.

"New Zealand has consistently taken a precautionary approach to keeping COVID-19 out," Hipkins said in a statement.

Australia and New Zealand began allowing quarantine-free travel less than a month ago, after a protracted run of zero locally-acquired cases in the neighbouring countries.

"Border controls ?are a key tool for stopping the introduction and spread of new cases from overseas and remain central to our elimination strategy," Hipkins said.

Australia has meanwhile barred travel from India due to high infection rates, but it has said it would begin chartering repatriation flights on May 15.  

(Reporting by Byron Kaye; editing by Jane Wardell) ((byron.kaye@thomsonreuters.com; +612 9171 7541; @byronkaye;))