New Zealand reported three new locally transmitted cases of coronavirus, as the cluster in its biggest city of Auckland expanded just days after authorities were forced to impose fresh curbs.

Prime Minister Jacinda Ardern lifted a brief Covid-19 lockdown in Auckland last week, saying the measures had helped limit the spread of the infection to a family of three.

However, a student from Papatoetoe High School in Auckland was reported to have tested positive for the virus earlier in the day. Health authorities later said that two siblings of the student were also infected with the virus, and have asked everyone linked to the school to get re-tested.

Officials have also called on people who had visited specific locations to self-isolate and call local health officials for advice on testing.