A 6.7-magnitude earthquake struck off New Zealand`s South Island on Tuesday, the United States Geological Survey said.

The tremor hit at 2:43 pm (0143 GMT) at a depth of 10 kilometres (6.2 miles) off the southwest tip of New Zealand`s South Island, according to the USGS.

Centred around 160 kilometres (100 miles) from mainland settlement Riverton, it was initially recorded as a 7.0-magnitude jolt before it was downgraded.

There was no tsunami warning or immediate reports of damage, according to the Honolulu-based Pacific Tsunami Warning Center.

New Zealand`s emergency management agency warned residents to avoid nearby coastal areas due to the risk of "strong and unusual currents".

"No land threat is expected," the agency said in a national advisory.

Rose Ivory, owner of La Riviera Guesthouse in Riverton, said her "whole car was rocking and rolling".

"That was quite a long one," she told AFP.

"Everyone was quite calm about the whole thing. I went into the grocery shopping, yeah, no one seemed to be too bothered about it."

Ben Sievwright, manager of Ziff`s Cafe and Bar in Invercargill on the South Island, said he felt "a little sway".

"Just a little wee shake, nothing too eventful," he told AFP.

New Zealand straddles the boundary of two major tectonic plates and is rattled by thousands of small earthquakes every year.

A magnitude 6.3 earthquake levelled swathes of Christchurch in 2011, killing 185 people, according to government figures.

Source: AFP