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©AFP / Greg Wood

A cyclist (C) inspects a damaged pharmacy in New Zealand's second largest city Christchurch

CHRISTCHURCH, New Zealand (AFP) - New Zealand braced for more destruction Sunday as aftershocks rocked the region following the most devastating earthquake in decades and as a powerful storm approached.

Civil defence officials warned that the ongoing aftershocks of up to 5.4 magnitude and the storm could threaten weakened buildings in the nation's second-largest city of Christchurch.

Central Christchurch remained cordoned off Sunday a day after the 7.0 quake struck just before dawn, damaging buildings and leaving much of the region without power, water and sewerage facilities.

©AFP/Graphic

Graphic showing location of a strong earthquake which hit New Zealand

Emergency evaluation teams picked their way through streets piled with rubble and littered with shattered glass to inspect buildings and determine whether evacuations were necessary.

Some coastal and riverside suburbs "are the worst-hit areas in the city and public health issues may yet force evacuations," civil defence said in a statement.

More than 200 people spent Saturday night in welfare centres while hundreds more sheltered with friends after fleeing their damaged homes.

Facts: Quake among New Zealand's worst

The Salvation Army said it was feeding 1,000 people and launched an appeal for those affected by the quake.

"New Zealanders are reeling from the disaster that struck Christchurch this weekend," Salvation Army national fundraising coordinator Major Robbie Ross said.

©AFP / Greg Wood

Officials warned that ongoing aftershocks of up to 5.4 magnitude and a new storm could threaten weakened buildings

"Not since the 1930s have we experienced an earthquake as severe and it is important that we do everything we can to help."

Prime Minister John Key has pledged government support, with initial damage estimates at two billion dollars (1.44 billion US).

"We are here to support them. We are not going to let Christchurch suffer this great tragedy on its own," Key said.

The earthquake was New Zealand's most destructive since the 1931 tremor in Napier which killed 256 people.

Although nobody was killed in the latest quake, civil defence warned the emergency was not over as more than 30 aftershocks hit the region within 24 hours of the main quake and were likely to continue for several weeks.

Related article: City 'wobbles like jelly' in powerful quake

©AFP / Greg Wood

Saturday's quake was the most destructive in New Zealand since the 1931 tremor in Hawke's Bay that killed 256 people

A forecast storm was also likely to bring fresh challenges to the city of 340,000 people.

"The strong winds could result in further damage to buildings and structures already damaged in yesterday's earthquake," the civil defence statement said.

"Rain is likely to create stormwater issues for already stressed city infrastructure as well as create problems for residents who have properties that have been damaged and may now be exposed."