A massive blast that targeted a convoy of Chinese workers in Pakistan’s largest city killed two nationals, Beijing’s embassy said Monday, in an attack claimed by a separatist group.

Beijing is a crucial ally for cash-strapped Pakistan but Chinese-funded infrastructure projects have sparked resentment and its nationals are routinely targeted by militant groups.

A “tanker” exploded on the airport motorway in the port city of Karachi around 11 p.m. (1800 GMT) Sunday, the regional government of southern Sindh province said on X.

Separatist militant group the Baloch Liberation Army (BLA) said in a statement that it had “targeted a high-level convoy of Chinese engineers and investors” coming from Karachi’s international airport.

Karachi borders Balochistan province, the largest but poorest region of the country, where billions of dollars have been funneled into transport, energy and infrastructure projects as part of the China-Pakistan Economic Corridor.

The BLA is waging a war of independence against the state, which it accuses of permitting unfair exploitation of resources by outsiders in the mineral-rich region.

In August, it carried out coordinated attacks across Balochistan that killed dozens of mostly Punjabis, the largest ethnic group in Pakistan, who were working in the region.

Beijing’s embassy to Pakistan said in a statement on Monday that two Chinese citizens had been killed in a “terror attack” on a convoy of personnel from the Chinese-funded Port Qasim power project.

The attack also left one Chinese and several Pakistani citizens wounded, the embassy said.

The embassy urged authorities to “conduct a thorough investigation of the attack and severely punish the killers, while at the same time taking practical measures to fully ensure the safety of Chinese citizens, institutions and projects.”

Beijing has repeatedly asked Islamabad to ensure the safety and security of Chinese nationals and its interests.

Pakistan’s foreign ministry said in a statement on Monday that it “reaffirms its unwavering commitment to the safety and security of Chinese nationals.”