(Update 1: updates with government statement, new death toll, changes throughout)

Islamabad, Jul 14 (EFE).- Pakistan's foreign ministry on Wednesday said that a bus explosion, in which 12 people were killed earlier in the day, was an accident and not an attack as reported earlier.

"This morning a bus carrying Chinese workers in Khyber Pakhtunkhwa Province, plunged into a ravine after a mechanical failure resulting in leakage of gas that caused a blast," the ministry said in a statement.

Nine of the 12 people killed in the incident were Chinese workers, who were traveling to their workplace along with three locals, the statement said.

The explosion was first attributed by the police to a bomb attack against the bus that was carrying Chinese engineers and workers to the construction site of the Dasu Hydraulic Power Project in Upper Kohistan region of the restive province.

The Water and Power Development Authority (WAPDA) of Pakistan is constructing the dam since 2018 jointly with two Chinese companies for civil and electro-mechanical works.

The Chinese embassy in Pakistan confirmed that the bus had "suffered" an explosion while heading to the dam.

"Pakistan is investigating the case," it said.

However, the embassy urged its citizens and companies in Pakistan to "pay close attention to the local security situation, strengthen the safety of project personnel, take strict precautions, and do not go out unless necessary."

The Dasu dam is part of the China-Pakistan Economic Corridor project (CPEC), a multi-billion dollar infrastructure project financed by Beijing with more than $60-billion in investment.

The CPEC, launched in 2015, finances the construction of a trade route that will connect the city of Kashgar, in northwest China's Xinjiang province, with the Pakistani port of Gwadar.

Gwadar is located in Baluchistan and will pave the way for China to access the Arabian sea.

In April this year, five people were killed and 15 injured in a car bomb attack in the parking lot of a luxury hotel in Quetta in the west of Pakistan.

The hotel was to host the Chinese ambassador to Pakistan Nong Rong, but he had not yet arrived when the blast occurred. EFE