At least nine Chinese nationals and four Pakistanis died in the powerful explosion in a explosion in northwestern Pakistan which targeted a bus carrying Chinese engineers and Pakistani soldiers.
Several others have suffered injuries and are in critical condition, Reuters reported.
The bus was carrying Chinese engineers who are working on the Dasu Dam. There were at least 30 engineers and workers travelling on the bus. There is a fear of the toll rising further as several injured are critical.
The Reuters report said that the bus plunged into a deep ravine after the blast and caused heavy losses and One Chinese engineer and one soldier is missing.
In a statement on Wednesday, the Chinese embassy said that "a certain project of a Chinese firm in Pakistan suffered an attack, which caused the deaths of Chinese nationals".
It urged Chinese firms to strengthen their security procedures and called for the swift arrest of the attackers.
Condemning the attack, Foreign ministry spokesman Zhao Lijian urged Pakistan to "severely punish" the perpetrators.