TAIPEI, Taiwan — Floods and mudslides unleashed by Typhoon Morakot last weekend have killed about 500 people on the island, Taiwan's president said today as he called on rescue crews to step up their efforts.

Morakot destroyed the homes of 7,000 people and caused agricultural and property damage in excess of 50 billion New Taiwan dollars, about $1.5 billion, President Ma Ying-jeou said at a national security conference, the first called since he took office 15 months ago.

He called it the most severe damage to the island in more than 50 years.

"While the rescue operation is still going on, we have started rehabilitation and reconstruction work, which is just as pressing as relief efforts but might be even more difficult and cumbersome," Ma said.

Morakot dumped more than 80 inches of rain on the island last weekend and stranded thousands in villages in the mountainous south. A total of 15,400 villagers have been ferried to safety, and rescuers are working to save another 1,900 people still stuck.