As many as 63 people have been killed following an earthquake in the city of Christchurch, New Zealand.

Prime minister John Key has told the county to expect the death toll to rise further, following the 6.3-magnitude quake last night.

“We may be witnessing New Zealand’s darkest day,” he told the country.

Up to 200 people are believed to be trapped under rouble across the city, with emergency services battling to rescue survivors.

Eye-witnesses described scenes of chaos in the aftermath of the quake, which struck at the relatively shallow depth of 3.1 miles below the surface.

Coming at 12:51 local time, the city was at its busiest, potentially pushing the death toll higher.

Christchurch

Nearly 400,000 people live in the country’s second city, with the epicentre of the quake recorded some ten kilometres to the south-east.

Christchurch Cathedral, an iconic stone building in the centre of the city, was partially destroyed. Footage from local television showed its spire toppling into the square below.

The Pyne Gould Guinness building was also destroyed, with as many as 30 people believed to be trapped inside.

Power was cut to thousands of residents, mobile phone networks were disrupted and road and rail transport was badly hit after the violent tremor, which tore gaping fissures in asphalt.

Rescue helicopters were used to pluck survivors to safety from the rooftops of buildings where staircases had collapsed.

Emergency workers – who had initially appeared overwhelmed - used giant cranes to pull office workers out of ruined city buildings.

Tourism

Christchurch is a popular tourist destination on the southern island of New Zealand.

Its close proximity to the Southern Alps ski-fields and international airport make the city a stopover destination for many visitors to the country.

The British Foreign Office issued a statement to citizens in the city: “Residents in Christchurch are being asked to stay off the roads to allow emergency services to get through. 

“Civil Defence is asking people to stay off their cellphones to allow calls from injured or trapped people to be able to get through to emergency services.

“They are also asking that if people are injured or trapped to keep trying on 111.

Christchurch Airport has, however, now re-opened. 

The Ferrymead Bridge is still impassable because of rising water, while Christchurch hospital is in operation. 

A Crisis Response Centre has been established at Christchurch Art Gallery.

Pacific Ring of Fire

The quake is the most deadly to hit New Zealand since a 7.8-magnitude tremor killed 256 people in the Hawke’s Bay region in 1931.

New Zealand was also struck last year, with a 7.0 magnitude quake reduced 100,000 homes in the Christchurch area to rouble on September 4th last year.

New Zealand sits on the Pacific Ring of Fire, a vast zone of seismic and volcanic activity stretching from Chile on one side to Japan and Indonesia on the other.