Six people have been killed after a suicide bomber rammed a vehicle into a convoy of Chinese engineers working on a dam project in north-west Pakistan, in the third significant attack on Chinese interests in the country in a week. The first two attacks targeted a Pakistani naval airbase and a strategic port used by China in the south-west province of Balochistan where Beijing is investing billions in infrastructure projects. The engineers were en route from Islamabad to their camp at the dam construction site in Dasu in the province of Khyber Pakhtunkhwa, said Mohammad Ali Gandapur, the regional police chief. “Five Chinese nationals and their Pakistani driver were killed in the attack,” Gandapur told Reuters. Dasu is the site of a large dam and the area has been attacked in the past. A blast on a bus in 2021 killed 13 people, including nine Chinese nationals. Chinese engineers have been working on a number of projects in Pakistan with Beijing investing more than $65bn (£51.4bn) in infrastructure works as part of the China-Pakistan economic corridor (CPEC) under Beijing’s wider belt and road initiative. No one claimed responsibility for Tuesday’s attack, nor was there a claim for the 2021 attack. Pakistan is home to twin insurgencies – one by Islamists and the other ethnic militants seeking secession. While Chinese interests are primarily targeted by the ethnic militants seeking to push Beijing out of mineral-rich Balochistan, they generally operate in the country’s south and south-west – far from the site of Tuesday’s attack. Islamists mostly operate in Pakistan’s north-west, the area where the convoy was attacked. Khyber Pakhtunkhwa police have reached the spot and started relief operations. A separate police source told Reuters the convoy was carrying staff of the construction firm China Gezhouba Group Company working on the Dasu hydropower project – the same company targeted in 2021. Construction work ceased for months after that attack. China’s embassy in Pakistan demanded investigations into the attack. “The Chinese embassy and consulates in Pakistan have immediately launched emergency work, demanding that the Pakistani side conduct a thorough investigation into the attack, severely punish the perpetrators, and take practical and effective measures to protect the safety of Chinese citizens,” the embassy said in statement. Shehbaz Sharif, the prime minister, is expected to visit Beijing next week, according to a source in the prime minister’s office, his first since taking office after February’s elections. A Pakistani military statement said the three attacks in the last week were aimed at destabilising the internal security situation, accusing “foreign elements” of aiding and abetting such incidents in Pakistan. It said strategic projects and sensitive sites vital to Pakistan’s economic progress were being targeted in an effort to sabotage it and sow discord between Pakistan and its allies, most notably China. Pakistan’s Indian Ocean port of Gwadar, on the route to vital Gulf shipping lanes, is managed by China, while nearby naval airbase Siddique is used to support security and development work, spearheaded by Beijing in Balochistan. Both were attacked in recent days by Baloch separatists. Ishaq Dar, the Pakistani foreign minister, condemned Tuesday’s attack and said Pakistan would continue to fight back against militants. Pakistan’s foreign ministry said the life and safety of Chinese nationals in Pakistan was of paramount importance. “Pakistan will continue to work with our Chinese brothers in ensuring the safety and security of Chinese nationals, projects and institutions in Pakistan,” it said in a statement.