A tsunami has hit New Zealand coast after a 7.8 magnitude earthquake struck its South Island.

The US Geological Survey said the quake hit just after midnight (11:02 GMT on Sunday), some 95 km (59 miles) from Christchurch.

The tsunami arrived in the north-eastern coast about two hours later. Officials said the first waves may not be the largest, with tsunami activity possible for several hours, according to a BBC report.

Residents were warned to head inland or for higher ground along the coast.

The ministry of civil defence has said the highest waves, which could be as tall as 5m are expected between Malborough, the north-eastern tip of the South Island, and Banks Peninsula, just south of Christchurch.

Police said they were investigating reports of a collapsed building in the coastal tourist town of Kaikoura.