'Better safe than sorry': police

Dunedin police adoped a "better safe than sorry" approach today amid a tsunami warning for New Zealand's east coast.

Police said at noon people in low-lying Otago coastal areas may be required to evacuate. 

"Information suggests that it's possible that larger waves may hit the coast over the coming hours. The police want to ensure people will be safe rather than sorry, and ask that they take sensible precautions," said Dunedin Emergency Response Commander, Inspector Alastair Dickie.

People living in low-lying coastal areas should be aware they may be required to evacuate, Inspector Dickie said.

South Otago police were also patrolling around beach areas to ensure that people stayed away from the coast.

Dunedin police closed city beaches this morning and began patrolling the coast after a tsunami alert for New Zealand's east coast. Authorities said there was no threat to the Otago coastline but warned of strong currents and unusual tidal effects over the following 12 hours.

Police staff were stood down at about 4.45pm, based on information from the Ministry of Civil Defence.

Otago Daily Times photographer Craig Baxter said the handful of swimmers at St Clair's Salt Water Pool at 8.45am were unaware of the tsunami alert shortly before police closed city beaches.

Several immediately left the pool after being informed of the situation.

A lifeguard at the pool told Mr Baxter he was keeping a watching brief and would evacuate the pool if necessary.

A 20cm wave hit the Chatham islands at 7.53am and the wave was expected to reach Dunedin at 9am.

Shortly after 9am, Mr Baxter said he saw a slight surge on St Clair beach after the water "went quite calm".

The water retreated "a couple of metres" and then small surge came back in, he said.

Dunedin civil defence chief Neil Brown told the Otago Daily Times this morning there was no threat to the city after a massive earthquake in Chile triggered Pacific tsunami warnings.

"I would be very surprised if anything was noted on the shoreline here. From very early on it was obvious the risk to Dunedin was nil," Mr Brown said.

"The maximum height predicted was less than a metre, and the time of arrival was approaching low tide. There is no on-shore affect with a 1m wave because it's within the range of the tide."

Mr Brown said even at high tide a 1m wave would not affect any property in Dunedin.

No civil defence action is being taken in the city.

Mr Brown assured the ODT that if there had been any risk then "quite significant" steps, including broadcasts, warnings and restricted access to beach areas, would have been initiated.

At Warrington surf lifesavers evacuated the beach and nearby camping area at 8.30am. A large crowd of sightseers had gathered at high points along Warrington's Esplanade to watch for waves arriving at the beach.