Sirens wailed and loudspeakers ordered residents of coastal towns and villages from Indonesia's Aceh province to Sri Lanka to seek safety during an Indian Ocean-wide tsunami practice drill on Wednesday.

The exercise, a U.N.-backed initiative to test the warning systems and overall preparedness of nations in the region, is supposed to simulate the magnitude 9.15 quake that struck off Aceh on Dec. 26, 2004 and triggered a huge tsunami.

About 230,000 people died as the tsunami raced across the Indian Ocean and hit Indonesia, Thailand, Sri Lanka and India, including 170,000 deaths in Aceh alone. In Aceh, several hundred took part in the simulation.

"I'm still traumatised from the tsunami," said Halimah, 43, who watched the drill but did not take part. "If there's another disaster, I prefer to take shelter in the mosque so that if I die, I'd die in the mosque."

Officials from Indonesia's meteorology and geophysics agency in Jakarta issued the test earthquake warning, sending out the notification of a major quake off the coast of Aceh via a telephone text message, followed by a tsunami warning.

People with mock bandages were carried on stretchers, while others pretended to be dead. Since the 2004 tsunami, early warning systems ranging from beach loudspeaker sirens to deep ocean monitor buoys have been set up at a cost of about $150 million, according to an official.

In the Sri Lankan fishing village of Godawaya in Hambantota, a vehicle blasted a piercing warning siren in the morning calm.

"The warning tower did not work. But the officials rang a siren from a vehicle and got the people together," fisherman Piyasiri Senaratna said.

"We all gathered at the Buddhist temple and the officials organised groups. This was successful exercise. We learned a lot about the tsunami from these officials."

In the eastern village of Puthukudiyiruppu South, where 13 people died in the 2004 tsunami, 45-year-old Sanmuaja Palmweu said there was much better awareness now of what to do.

"Before 2004, we knew nothing about tsunamis, but thanks to all the drills and training we know what to do now, and how to pass the information if something is coming," said Palmweu.

TOP ACEH OFFICIAL PROCLAIMS DRILL A SUCCESS

Some officials appeared confused during the Aceh drill, but the province's deputy governor declared it a success, while warning against excessive reliance on technology. U.N. officials are to issue an assessment within days.

A series of recent disasters in Asia has raised fresh questions over the state of preparations — including an earthquake on Indonesia's Sumatra island, and a series of tsunamis in Samoa and American Samoa.

Some experts have questioned the effectiveness of early alert systems, particularly if the time interval between the alarm and the tsunami hitting the area is very short, as would be the case in Indonesia, which lies on the fault lines.

Tsunami waves can travel at speeds of 800-1,000 kph (500-600 mph. The height of normal waves and tsunami waves is similar in deep ocean water, but closer to the shore, tsunami waves slow and swell, reaching heights of 10 metres (32 feet) or more.