[Nicke]

BANKGOK (AFX) - The authorities here said they are 'satisfied' with their tsunami warning system, having hours earlier sounded an alarm following a major earthquake in the Nicobar islands in the Indian Ocean.

The warning was issued shortly before midnight, prompting police to help evacuate thousands of people to higher ground along the six provinces pounded by the Dec 26 tsunami. It was withdrawn about 90 minutes later at 1.20 am.

The National Disaster Warning Center triggered its alert shortly after the US Geological Survey said a 'major' earthquake measuring 7.0 on the Richter scale hit the remote Indian island chain at 1542 GMT Sunday.

Thai authorities cut into local television programming to issue emergency broadcasts that said the earthquake was about 660 kilometers west of the resort island of Phuket, whose west coast was hard hit in December's disaster.

Some residents along Phuket's Patong beach said they heard loud sirens, part of the newly developed warning system, for about 30 seconds before deciding to flee, along with thousands of other residents and Western tourists.

Major General Jaruek Sriwarit, a member of the National Disaster Warning Center, said the center's officials were 'satisfied' with the system, particularly the way television stations passed on the emergency information.

'We don't think it was an overreaction,' Jaruek told Agence France-Presse.

'We were happy that we issued the warning to people because if there was a tsunami, it would take less time (to reach the coast) than the December 26 tsunami because it was only 600 kilometers from Phuket.'

Prime Minister Thaksin Shinawatra said the warning system remains work in progress but defended the country's decision to announce an alert, even as India and Sri Lanka, two countries hard hit in December's disaster, declined to issue tsunami warnings.

'A tsunami does not automatically happen, but if the earthquake is strong enough there is a possibility,' Thaksin told reporters.

Yet the premier acknowledged that too many false alarms may cause people to ignore the real thing.

'We are concerned that (too many tsunami warnings after earthquakes) will make people not believe the next warning when it happens,' he said.

Thailand will 'speed up' its installation of tsunami-detection buoys in the Indian Ocean, a key link in the warning system, in order to better predict the giant waves, Thaksin said.

Jaruek said the overnight warning was a vital dress rehearsal.

'We can count this as a big trial because the first time we issued the warning, people panicked,' he said. 'This time, they were in control of themselves and knew what they should do.'

The false alarm was the second for tourist-magnet Thailand since the huge Dec 26 waves killed some 5,400 people in the country, about half of them foreign holidaymakers.

The first, on March 29, sent thousands of tourists scrambling to higher ground after a massive undersea quake off the Indonesian coast.