A tsunami warning system is now in place for Indian Ocean countries, but experts said Wednesday there is still room for improvement in methods to convey the alerts to coastal communities.

A tsunami that killed 600 people in Indonesia two weeks ago exposed some shortcomings in a system still being built after the Dec. 26, 2004 disaster that killed almost 217,000 people in a dozen Indian Ocean countries, experts at a U.N.-backed meeting said.

Two international agencies issued warnings that the powerful sub-sea earthquake on July 17 could spawn destructive waves crashing into Java's southern coasts. But Indonesian officials in the capital, Jakarta, did not pass them on to local communities in time.

"The system is only as good as the response," Joseph Chung of the U.N.'s International Strategy for Disaster Reduction said after the three-day meeting to assess progress on the $126 million Indian Ocean Tsunami Warning and Mitigation System.

Patricio Bernal, executive secretary of the U.N's Intergovernmental Oceanographic Commission, described last month's disaster as "very frustrating."

Nineteen months after the 2004 carnage, 23 monitoring stations have been put in place in the Indian Ocean to quickly measure the strength of underwater quakes and assess the tsunami threat.

That information is sent to the Hawaii-based Pacific Tsunami Warning Center and the Japanese Meteorological Agency, which then relay it to individual countries at risk.

Bernal said an assessment must be conducted to determine areas and populations that are most vulnerable. Then, he said, local officials must draw up plans for their area — such as how to involve police or military, and whether to install loudspeakers.

"You have to have a real down-to-earth plan on how to do it," he said. "There's no way that the central authority can do that."

Indonesia, Pakistan and Iran are especially vulnerable to tsunamis because they are near tectonic fault lines, meaning waves can slam into coastlines within minutes of a quake.

In those countries, especially quick reaction times must be built into training, said Peter Koltermann, of UNESCO's tsunami unit.

In Indonesia "nobody has time to think because time is short," he said. "Here the system is tested at full speed and no excuses."

Some experts said children in coastal communities should learn about the threat of tsunamis in school, while signs on beaches and cards inside hotel rooms should advise people to quickly move away from the coast if they feel an earthquake.

Leaders in vulnerable villages should have plans in place to quickly move vulnerable populations — such as the elderly or young children — away from the shore, experts said.

Jan Sopaheluwakan, a geologist at the Indonesian Institute of Sciences, said plans being discussed for the country included installing sirens on cell phone towers and including mosques and harbor authorities in warning plans.

Officials also plan to better utilize television and radio stations to get warning messages out faster.