Within weeks, mobile phone operator Dialog Telekom says it was working on ways to solve the problem.

"If we go back to Dec. 26, many lessons were learnt," Dialog chief executive Hans Wijayasuriya said at the launch of the mobile phone-based warning system on Monday.

"You can convert a mobile phone into a powerful alarm device."

The scheme will be launched first as a pilot project in parts on the island's south coast, much of which was devastated by the giant wave that killed nearly 40,000 Sri Lankans.

It will use text messages to alert police officers, village chiefs and other important officials to warnings, and can also send a blanket message to all phones in an area through "cell broadcasting" -- more versatile than a normal text or phone call.

"What usually happens in a disaster is that the network is overloaded and calls don't get through," Dialog research and development manager Ravi Abeysekera told Reuters. "That isn't a problem with cell broadcasting."

The system could be running island-wide by the middle of 2006, he said. In the aftermath of the disaster, Sri Lankan officials put up "tsunami zone" signs in some coastal areas advising residents of the best route to higher ground.

Holland had developed a similar disaster warning system, Abeysekera said, but the technology was still in its infancy.

Lessons learnt in Sri Lanka could be applied to cities like New York or London in the event of a chemical spill or a terrorist attack.

Some 3.5 million of Sri Lanka's 19 million people have a mobile phone, but to reach a wider number the system will also use alarms linked to the mobile phone network that will trigger sirens or bells in police stations, churches and temples in the event of an alert.

Government officials will control the alert system from the capital Colombo.