A state of emergency has been declared in Christchurch on New Zealand’s South Island as former cyclone Gita approaches the country.

Air New Zealand cancelled all flights in and out of the capital, Wellington, on North Island.

The airline warned of “significant disruption” to services in and out of Wellington including the cancellation of flights to and from Sydney and Melbourne.

Dozens of schools have been shut and roads closed as the South Island braces itself for the storm, which is due to make landfall today.

Residents were told to expect floods and winds of up to 90mph for at least 12 hours as power cuts affected 14,000 people.

“The full impact of the storm will be felt overnight and tomorrow morning,” said Christchurch mayor Lianne Dalziel.

She urged residents in low-lying areas to evacuate, saying: “We are expecting homes to be flooded.”

The ex-cyclone, which has since been downgraded to a storm, last week left a trail of destruction in the Pacific island nations of Tonga and Fiji.

Tonga is reeling from the storm which hit the overnight, injuring people and destroying buildings, including the parliament.

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