A state of emergency in New Zealand’s earthquake-hit city of Christchurch has been extended after a massive aftershock.

The 5.0-magnitude aftershock struck just below the surface at 07:49 local time yesterday sending people rushing into the streets, briefly cutting power supplies and bringing down debris from already damaged buildings.

The latest aftershock was half a mile deep and closer to the centre of the country’s second largest city than Saturday’s 7.0-magnitude quake, which caused billions of dollars of damage.

Civil defence minister John Carter said almost 300 aftershocks had rocked the area since Saturday.

The recovery period for the city of 340,000 people would be “months, not weeks,” he added.

Travellers planning to visit Christchurch were already being advised to postpone their plans unless it is essential they visit the area.

Regular tourism updates will be carried on www.newzealand.com and www.christchurchnz.com.