The exercise, code-named Pacific Wave '06, was initially declared a success by officials at the Pacific tsunami Warning Centre in Hawaii, who said a series of earthquakes hitting the region for real had not disrupted the test.

"If those events were large enough to cause a tsunami warning to be issued then we would have terminated the test at that point," duty geophysicist Stuart Koyanagi told AFP.

A magnitude 7.4 earthquake struck off the coast of New Zealand's Kermadec Islands late Tuesday, just hours before the test began, the US Geological Survey (USGS) reported.

A 6.8 magnitude earthquake then struck near Indonesia's Nias island at 1528 GMT Tuesday and two temblors of magnitude 5.8 and 6.0 struck Tonga after the exercise began at 1900 GMT with a mock 9.2 quake off Chile, the USGS said.

The warning centre in Hawaii, which launched the test exercise for more than 30 countries, said none of the earthquakes triggered genuine Pacific-wide tsunami warnings, but the two biggest could cause small local tsunamis.

There were no immediate reports of casualties or damage from the earthquake zones.

Of more concern to test organisers was news later that plans to alert emergency coordinators to tsunami threats failed to work in Thailand when busy cell phone networks took hours to deliver key messages.

"The problem we faced was with communications. We have no idea whether our messages sent to local operations chiefs by fax and SMS arrived on time or not, and by midday some of them said they did not recieve the SMS," Pakdivat Vajirapanlop from the National Disaster Warning Center told AFP.

"We need to know whether they have received our messages. What can they do if the messages don't arrive on time? Then the warning is useless," said Pakdivat, the center's deputy operations chief.

The Pacific tsunami Warning System (PTWS) test was part of an effort to strengthen defences following the December 26, 2004 killer waves that swept across countries in the northern Indian Ocean, killing around 220,000 people.

Koyanagi, speaking before news of the warning delays in Thailand, admitted there were some areas where communications would need to be improved.

This mainly involved small island nations in the South Pacific, where communication systems were not well developed.

"I think for the first test there may have been a few that we had difficulty getting through to.

"The fact that the test ran for a pretty long period of time allowed us to backtrack and eventually get hold of just about everybody," he said.

The exercise began with a mock alert about the quake off the coast of Chile, which theoretically sparked a tsunami across the eastern Pacific. The second phase of the test involved a fake quake north of the Philippines.

Some countries, including the Philippines and Malaysia, staged partial evacuations as part of the exercise.

In the Philippines, civil defense officials evacuated the coastal village of Buhatan in the Bicol peninsula, 340 kilometers (212 miles) southeast of Manila, early Wednesday, taking all 1,143 residents to higher ground.

The drill took place before the simulated tsunami from the Chile quake was due to reach the shores of the western Pacific, the government seismology office said.

The alert message was successfully passed from regional to provincial to local officials, seismologist Esmeralda Banganan of the Philippine Institute of Volcanology and Seismology told AFP.

In New Zealand, where false media reports of a tsunami caused panic earlier this month, officials spent the day in the crisis management centre beneath parliament.

"The major lessons learnt today are not about process, they have been about management decisions," the director of the Ministry of Civil Defence and Emergency Management John Norton said.

The Pacific tsunami Warning System has been in existence for more than 40 years, but exercises have until now only been conducted at national or local level.

The PTWS comes under the aegis of UNESCO's Intergovernmental Oceanographic Commission, which last year also set down the foundations for a tsunami early warning system in the Indian Ocean.

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