Tsunami alert after NZ earthquake !

A strong earthquake has shaken New Zealand, generating a small tsunami and briefly putting the country on alert.

The US said a 7.8-magnitude quake hit off the south-west tip of New Zealand, 161km (100 miles) west of Invercargill at a depth of 33km.

The Pacific Tsunami Warning Center in Hawaii detected a small tsunami and issued a warning for New Zealand.

It later cancelled the warning, but said there could have been some damage in areas near the epicentre.

There has been no word of damage from either the earthquake or any tsunami, although reports said the quake was felt across New Zealand's South Island.

"An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines in the region near the epicentre within minutes to hours," the warning centre said in a statement after the quake was detected.

The quake was detected at 2122 local time (0922 GMT), reports said.

The US Geological Survey (USGS) and Japanese seismologists classified the quake as a 7.8-magnitude event, but authorities in New Zealand suggested it could have been weaker.

"We've had big differences in the measurements of the quake," the country's national civil defence centre said in a statement, saying New Zealand's Institute of Geological and Nuclear Science measured it at magnitude 6.6.

A second earthquake, provisionally measured at magnitude 5.8 by the USGS, was detected shortly after the first event.

In Hawaii, the Pacific Tsunami Warning Center said ocean buoys had detected an increase wave size in the aftermath of the quake.

The centre said the sea level was amplified by 17cm (6.7in) after the earthquake, with waves passing every 10 minutes.

Even though we are maybe 400km from the epicentre this was easily the longest and biggest I have ever felt Simon Darby South Island resident History of deadly earthquakes How earthquakes happen Animated guide: Tsunamis

"Sea level readings confirm that a tsunami was generated," it said in a statement.

"This tsunami may have been destructive along coastlines of the region near the earthquake epicentre."

Alerts were issued for a string of New Zealand coastal towns and cities.

New Zealand's Herald newspaper reported that the quake was felt across the South Island.

People ran from restaurants in Queenstown as buildings shook, the newspaper said. Power and phone lines were severed in some places.

One South Island resident, Simon Darby, told the newspaper the quake lasted about two-and-a-half minutes.

"I lived in Tokyo for three years so I know what large quakes are like. Even though we are maybe 400km from the epicentre this was easily the longest and biggest I have ever felt," he said.

"It wasn't very violent, more of a rolling feel. But it had a power about it - I ran straight outside into the car park."

BBC NEWS REPORT