People living near the towers in some provinces had not been informed and were surprised by noises emitted by the towers yesterday morning. The test was cut short.

National Disaster Warning Centre director Smith Dharmmasaroj said provincial governments had not informed residents.

The centre planned to test 79 signal towers in Krabi, Phuket, Phang Nga, Ranong, Trang and Satun on a daily basis at 9am, starting yesterday. It also plans a large-scale system test and evacuation drill in about three months.

Smith said the centre would restart testing when it was informed all residents had been notified. Tests will probably resume after the Songkran festival.

A hundred towers have been built along the Andaman coast, and another 48 will be constructed in Gulf of Thailand provinces.

Central, North and Northeast Thailand will have 82 towers to alert people to floods and air pollution. Towers have been erected in Mae Hong Son, Chiang Rai and Chiang Mai and will be tested in April and May.

Phuket Disaster Prevention and Mitigation chief Arun Kerdsom said yesterday's first round of tests for the island's 19 towers had gone well. Phuket residents had been informed, and the test did not cause panic.

Sirens were audible for just 50-70 metres. The test included a short signal followed by five 30-second sound checks, Arun said.

Arun said the Phuket towers had worked well. Previous daily testing had been silent. Relief workers are drilled daily too.

The Andaman coast was hit by the December 2004 tsunami, which killed more than 5,000, including foreign holidaymakers. Another 11,000 were injured.