PHNOM PENH, July 25 (Xinhua) -- Flash floods triggered by the collapse of a hydropower dam in southern Laos have hit 17 villages in Stung Treng province in northeastern Cambodia, a spokesman said on Wednesday.

Cambodia's Siempang district in the province is about 187 km downstream of the collapsed Xepian-Xe Nam Noy dam in Laos.

"More than 5,000 families living in those villages in four communes are being affected from the flash flooding," Keo Vy, a spokesman for the National Committee for Disaster Management (NCDM), told Xinhua.

"Our authorities have evacuated some 1,289 families with 5,619 people to safe places, as the rest of the affected families do not want to leave their homes citing a slow rise of water levels," he said.

According to the spokesman, the water levels on the Sekong River in Siempang district rose to the alarm level of 11.5 meters on Wednesday evening, up from 11.3 meters in the morning.

Keo Vy said that there was no report of casualties in the Cambodian side thanks to a swift rescue operation taken by local authorities.

The dam, located on Xepian and Xe Nam Noy rivers in Champasak province and Attapeu province of Laos, collapsed on Tuesday and unleashed flash flooding into the Xepian river, affecting six villages in Attapeu province's Sanamxay district.

The Xepian river and Xe Nam Noy river flow into the Sekong River, a major tributary of the Mekong River, in Cambodia's Stung Treng province.