For the last 18 months, the Intergovernmental Coordi-nation Group for the Indian Ocean Tsunami Warning and Mitigation Warning System has worked on how to link up weather centres in member states and place modern tsunami detectors around the region.

The group was formed after the December 26, 2004 Indian Ocean tsunami that killed 230,000 people.

Almost all Indian Ocean nations, through their weather centres, are now connected and member states have ambitious plans to float tsunami detecting buoys, place modern seismographs and erect siren towers to signal coming waves.

But experts say a July 17 tsunami that killed more than 600 people in Indonesia showed advanced technology may not be enough to save people without a clear rapid response plan.

"The system is only as good as the response. What to do when we receive the message?" Joseph Chung, a senior regional officer at the United Nations International Strategy for Disaster Reduction, told a news conference.

An Indonesian minister said top officials received an alert 17 minutes after the undersea quake that triggered the Java tsunami, but the warning failed to prompt rapid responses due to lack of preparedness at the grassroots level and a rigid bureaucracy.

"The dramatic events of July 17 have highlighted for the first time the dimension of what is needed," Patricio Bernal, Executive Secretary of the Intergovernmental Oceano-graphic Commission, told reporters.

Jan Sopaheluwakan, vice chairman of the Indian Ocean tsunami warning group, said scientists must devise warnings that could be understood at the grassroots level.

"We have to start from turning a message that comes from technical, scientific information which is rigid and cold to something understandable without giving room for interpretation," the Indonesian geologist told Reuters.

"The system must focus on the human side. The decision makers, the regents, the mayors, the legislators must understand a tsunami early warning system is not a magic box that will work instantly after it is in place."

The Java tsunami was a wake-up call for some local administrations, including the Bali government which will run tsunami drills this week at two popular tourist beaches.

Indonesia also plans to place sirens on around 500 cellular phone towers in vulnerable areas in the world's largest archipelago and assign 75 seaports to send signals in case of a possible tsunami.