"Getting aid to the millions of victims of the tsunami is a race against time," Annan told world leaders at the one-day summithere aimed at coordinating the massive relief and reconstruction efforts for the earthquake and tsunami hit countries.

"Millions in Asia, Africa, and even in far away countries, are suffering unimaginable trauma and psychological wounds that will take a long time to heal. Families have been torn apart," Annan said, adding that "the disaster was so brutal, so quick, and so far-reaching, that we are still struggling to comprehend it."

He also called for the establishment of a tsunami warning system in the Indian Ocean, saying "Although we were powerless to stop the tsunami, together we have the power to stop those next waves."

"Prevention and early warning systems must become a priority," he stressed.

Although world pledges has exceeded 3 billion dollars, people still don't know if the pledges can be honored.

Australia Wednesday raised its total aid pledge to 810 million US dollars, topping Germany's 660 million, followed by Japan's promised 500 million and the United States' 350 million.