Senior Chinese diplomat Wang Yi urged Pakistan to investigate a blast on a bus that killed 13 people, including nine Chinese workers, but stopped short of calling it an attack, according to a post on Thursday on the foreign ministry's website.
A Chinese foreign ministry spokesperson called the Wednesday blast a bomb attack later that day but Pakistan said a mechanical failure caused a gas leak that led to the explosion.
The blast sent the bus crashing into a ravine in Khyber-Paktunkhwa province in northwest Pakistan where Chinese engineers have for several years been working on hydroelectric projects as part of Beijing's Belt and Road Initiative.
China is a close ally and major investor in Pakistan and various militants fighting the Pakistani state have in the past attacked Chinese projects.
Wang told Pakistani Foreign Minister Shah Mahmood Qureshi that if it was indeed a "terrorist attack", Pakistan should immediately arrest the culprits and punish them severely, according to the Chinese ministry's summary of a meeting they had in Dushanbe on Wednesday.
Wang, who is China's State Councillor and foreign minister, said "lessons should be learned" and both sides should further strengthen security measures for China-Pakistan cooperation projects to ensure their safe and smooth operation.
The two spoke in Dushanbe, the capital of Tajikistan, on the sidelines of a foreign ministers meeting of the Shanghai Cooperation Organisation.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)