Tenaga Nasional Berhad (TNB) was forced to release water in stages as the water level in the Sultan Abu Bakar dam, Cameron Highlands, rose sharply and reached a critical level within a short time, following heavy rains on Wednesday.

In a statement here Thursday, TNB said the unusually heavy rains since 6pm on Wednesday, caused flash floods in Ringlet which carried garbage into Tasik Ringlet.

TNB had to activate the Emergency Response Plan (ERP) when the water rose rapidly, with the rate of increase in the water level in Tasik Ringlet reaching seven feet per hour.

This increase was significantly higher when compared with the level of three feet per hour when the mud flood occurred last year, said the statement.

The TNB warning siren in Bertam Valley sounded at 8.15pm for evacuation as the water level stood at 3,507.4 feet, and the siren at the Sultan Abu Bakar Dam also sounded a warning of danger at 8.40pm.

"TNB informed the security, local authorities and village heads of Bertam Valley, before the water was released at the level of 3,510 ft. The water discharge was made after receiving feedback from the Ringlet police station that the evacuation had been completed and the release of water can be carried out," said the statement.

TNB Cameron Highlands Power Stations general manager Mohammad Zaki Jalaludin said: "We are grateful the evacuation went smoothly as a result of an integrated ERP training undertaken during the year.

In the meantime, he said, following the weather forecast it was going to rain in the next few days, the dam water would continue to be released until it was down to a safe level.

In the 6.30pm incident Wednesday, three people, including a 13-year-old boy died and five others were injured as a result of mudslides in Ringlet.

The incident affected 203 people from 47 families in Kampung Baru and Bertam Valley, with 20 houses and 20 vehicles damaged.