By Asif Shahzad

ISLAMABAD (Reuters) - Pakistan's prime minister called on Wednesday for a joint investigation by military and civilian officials into a suicide bombing that killed five engineers from China, while reviewing security arrangements for its projects, officials said.

Tuesday's incident was the third major attack in 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.

Prime Minister Shehbaz Sharif called for "a thorough joint investigation to be conducted, utilising all resources of the state," his office said in a statement.

There was no immediate claim of responsibility for Tuesday's 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.

Two previous attacks targeted a naval air base in Pakistan and a strategic port used by China in the southwestern province of Balochistan, where Beijing has poured billions of dollars into infrastructure projects.

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

Pakistan has set up a dedicated force of police and military to ensure security for Chinese activities, officials say.