ISLAMABAD: All workers were evacuated safely from Pakistan’s Tarbela Dam after a weak rock mass there collapsed during excavation work, an official said on Monday, allowing water to surge into a tunnel and powerhouse.

Waseem Ahmed, deputy commissioner of the northwestern Haripur area where the dam is located, said a weak section of the rock collapsed during work at the second bench of the connecting tunnel at Tarbela Fifth Extension Hydropower Project on Monday.

“It allowed water from the intake pit to enter the tunnel,” Ahmed told Arab News. “All workers were immediately evacuated and are safe.”

The Water And Power Development Authority (WAPDA) said in a separate statement that water from the intake pit has been completely drained, while dewatering the under-construction powerhouse has started.

Ahmed rejected reports on social media that claimed the dam had broken.

“If the dam had broken, it would have caused flooding downstream,” he said. “As I speak to you, the water level inside the tunnel has almost completely receded.”

State broadcaster Radio Pakistan reported that senior WAPDA officials, the project engineer and the contractor are assessing the situation to address any challenges to the project.