WELLINGTON - A state of emergency was declared on Monday in New Zealand's capital of Wellington, as torrential rain triggered severe flooding and landslides, and a man was unaccounted for.

Police are searching for Philip Sutton, a man in his 60s from the suburb of Karori, who was reported missing after floodwater and debris impacted his home, said a police statement.

The region remains under a high-risk red heavy rain warning until Tuesday night, according to the country's meteorological service.

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Residents in low-lying and flood-prone areas have been told to self-evacuate for the next 24 hours, despite no mandatory evacuations so far. An emergency assistance center has opened for those displaced.

Some areas in the lower North Island are still cleaning up from flash floods that occurred on Sunday.