Chinese investigators arrived in Pakistan on Friday to join a probe into the killing of five Chinese nationals in a suicide attack, Pakistan's interior ministry said, seeking to stem assaults threatening Islamabad's drive to modernise the economy.

Tuesday's incident was the third major attack in little over a week on China's interests in the South Asian nation, where Beijing has invested more than $65 billion in infrastructure projects as part of its wider Belt and Road initiative.

Pakistan's Interior Minister Mohsin Naqvi met the Chinese team of investigators at Beijing's embassy and briefed them on the investigation so far, the statement said.

In late 2022, the two allied countries started a joint investigation into an attack that year on China's nationals and its interests, which have seen a rise in recent months.

There was no immediate claim of responsibility for the latest attack, in which a suicide bomber rammed a vehicle into a convoy of Chinese engineers working on a hydropower project at Dasu in Pakistan's northwest, killing six people.

The bombing followed a March 20 attack on a strategic port used by China in the southwestern province of Balochistan, where Beijing has poured billions of dollars into infrastructure projects, and a March 25 assault on a naval air base, also in the southwest. Both attacks was claimed by the Baloch Liberation Army (BLA), the most prominent of several separatist groups in Balochistan.

Dasu, the site of a major dam, has been attacked in the past, with a bus blast in 2021 killing 13 people, nine Chinese among them, although no group claimed responsibility.

Chinese contractors suspended work on three hydropower projects in view of security concerns after Tuesday's attack, a government official said, adding that it was a routine practice after such incidents.

Pakistan is home to twin insurgencies, one mounted by Islamist militants and the other by ethnic separatists who seek secession, blaming the government's inequitable division of natural resources in southwestern Balochistan province.

Chinese interests are under attack primarily by ethnic militants seeking to push Beijing out of mineral-rich Balochistan, but that area is far from the site of Tuesday's bombing.

Pakistan has set up a dedicated force of police and military to ensure security for Chinese activities, officials say. (Reporting by Asif Shahzad, Editing by William Maclean)