A fire ripped through the camp of a Chinese company managing the construction of a remote hydropower dam in northwestern Pakistan on Tuesday, officials said.

Since 2015, Beijing has poured billions of dollars into Pakistan under an investment scheme known as the China Pakistan Economic Corridor (CPEC).

Private firms have also flooded over the border to service contracts on ambitious infrastructure projects, despite persistent threats from Pakistani militants.

Police said Tuesday's pre-dawn blaze ruined a warehouse complex for the Dasu hydropower project in the Kohistan district of northwestern Khyber Pakhtunkhwa province, 180 kilometres (110 miles) north of Islamabad.

"It was a huge fire," a Rescue 1122 official at the site told AFP. "Initially, the flames were very high and we had to call for fire brigade vehicles from two other districts."

"It was quite a big storehouse, and apart from oil drums, stationery and machinery were also stockpiled there. That's all been destroyed in the fire," he added.

In 2017, Pakistan's water ministry awarded the construction contract for the Dasu dam to the China Gezhouba Group Company.

The camp housed Chinese engineers, surveyors and mechanics, but both police and Rescue 1122 said none were injured or killed.

One police official said an electrical fault was the suspected cause of the fire.

In July 2021, 12 people -- including nine Chinese workers -- were killed aboard a bus carrying staff to the Dasu site, with Beijing insisting it was a bomb attack.

Islamabad initially blamed the explosion on a "gas leak", but security at the site was dramatically ramped up in the aftermath.

Despite close economic ties, the security of Chinese workers in Pakistan has long been of concern to Beijing, with militants resentful of foreign influence putting Chinese nationals in their crosshairs.

Since the Taliban surged back to power in neighbouring Afghanistan, Pakistan has witnessed a dramatic uptick in militant attacks in its western regions -- the same areas where China is focusing investment.