The search continues for missing people after a landslide hit a popular campsite in Mount Maunganui, on New Zealand's North Island.

Six people remain unaccounted for, and police are seeking information on another three. Two teenagers are among the missing, with the youngest aged 15 years old, police said.

Another landslide at the nearby Welcome Bay killed a grandmother and her grandchild, public service broadcaster Radio New Zealand (RNZ) reported. One of them was a Chinese national, police told reporters on Friday.

The landslides come after heavy rain pummelled parts of the North Island for days.

Prime Minister Christopher Luxon, who visited the disaster site on Friday, said it was "inspiring" to see the support pouring through the community, with neighbours and "friends of friends of friends" helping to clear debris in flood-hit areas.