WELLINGTON (AFP) - A strong 6.8-magnitude earthquake hit New Zealand's South Island on Friday, the US Geological Survey said, but no tsunami warning was issued.

The USGS said the quake, which struck at about 0230 GMT (10.30 am Singapore time), was 5km east of Seddon, close to the centre of a series of quakes last month.

The tremor was felt strongly in the capital Wellington.