The city of Christchurch in New Zealand has been rocked by a powerful aftershock, stemming from a major quake which hit on Saturday.

The aftershock caused some damage to the city, still reeling after the extensive damage caused to buildings across the city last week.

Residents rushed into the streets as the aftershock hit.

The power of the shock was accompanied by cuts in power supplies and the dislodgement of loose material from the already damaged buildings.

A number of motorists in a 2 kilometre tunnel linking Christchurch to the nearby port of Lyttleton were frightened by the aftershock, which opened up cracks in the structure.