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

Morakot left 7,000 people homeless and caused agricultural and property damage in excess of $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 50 years.

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

• Click here for photos.

Video: Click to watch a report from FOX News' Amy Kellogg.

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.

Ma said the death toll includes 120 confirmed deaths, and about 380 people believed to be buried in the debris of a landslide in Shiao Lin, the hardest-hit village.

Authorities have given up hope of finding anyone alive under the tons of mud that now cover Shiao Lin, Kaohsiung county chief Yang Chiu-hsing said. Instead of digging into some 170 mud-buried homes, a memorial park will be built on the site, he told reporters.

With rising public complaints about the slow rescue work, the government said its operations have been hampered because many areas of the country were cut off when roads and bridges collapsed.

Rescuers have relied on helicopters to reach the worst-hit areas, and on Thursday authorities requested larger choppers from foreign governments capable of carrying earth-moving equipment and shelters.

Many villagers have conducted their own rescue operations. More than 20,000 troops have joined civilian workers on rescue, cleanup and rehabilitation work, officials said.