Pakistan apprehended over 12 people linked to the suicide bombing that killed five Chinese engineers and their Pakistani driver last week, a senior police source told AFP on Tuesday.

The engineers and their driver were on their way to the Dasu hydroelectric dam, which is being built by a Chinese company in northwest Pakistan when a suicide bomber collided with their vehicle and detonated.

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"More than a dozen suspected individuals have been taken into custody," the source told AFP on condition of anonymity. "Among the apprehended suspects are some Afghan nationals."

Islamabad has attributed a recent increase in attacks in Pakistan to neighboring Afghanistan, accusing the Taliban government there of not containing affiliated militants.

The Taliban government repeatedly denied sheltering the armed groups or providing them safe places. But the source told the news site that "initial evidence suggests the involvement" of Pakistan's domestic Taliban faction, which is considered to have strong connections with the Afghan Taliban according to analysts.

The organization, Tehreek-e-Taliban Pakistan (TTP), publicly rejected any involvement in the attack that occurred last Tuesday.

China is Islamabad's closest regional partner and a significant investor in the country's struggling economy. However, Chinese citizens have often been attacked by Islamist militants in recent years.

The bombing prompted Islamabad to engage in series of diplomatic efforts to safeguard the billion-dollar investments pledged by Beijing under its "Belt and Road" initiative.

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Following the attack, China's Foreign Ministry called on Pakistan to "thoroughly investigate the incident as soon as possible, hunt down the perpetrators, and bring them to justice".

A Chinese investment expert at COMSATS University in Islamabad, Azeem Khalid said "The Chinese workers were already scared and feared" that another attack was coming. "With every such incident, the speed of the project will be slower," he added.

Yesterday, Prime Minister Shehbaz Sharif visited Chinese workers at the Dasu construction site and stated that his country is committed to ensuring their safety and "will not leave any stone unturned" to guarantee that.

"I will not rest until we have put in place the best possible security measures," he told workers. "I can assure you that our strong hands will catch the culprits very soon."