Prime Minister Shehbaz Sharif speaks to the media. File photo

Attacks by separatist militants in Pakistan's southwestern province of Balochistan, aimed at stopping development projects that form part of the China-Pakistan Economic Corridor (CPEC), Prime Minister Shehbaz Sharif said on Tuesday.

The assaults begun on Sunday, killing more than 70, were the most widespread in years by ethnic militants seeking to win secession of the resource-rich province, home to major China-led projects such as a strategic port and a gold and copper mine.

"The terrorists want to stop CPEC and development projects," Sharif said in a televised address to cabinet, adding that the purpose was also to drive a wedge between Islamabad and Beijing.

CPEC, said to have development commitments worth $65 billion, is part of Chinese President Xi Jinping's Belt and Road initiative.

Residents finalise preparations for the funeral of the shooting victims in Musakhail district, Balochistan on Monday. AFP

Pakistan has not been able to fully build the infrastructure needed to tap mineral resources in poverty-stricken Balochistan, and has sought China's help in developing the province.

In the past, Beijing has flagged concerns about the security of its citizens working on projects in Pakistan, particularly in Balochistan. Six Chinese engineers working on a dam project were killed in March in the northwest.

Separatist militants have consistently targeted Balochistan's deepwater port of Gwadar, run by China.

A militant group, the Balochistan Liberation Army (BLA), took responsibility for this week's simultaneous attacks on police stations, railway lines and highways in the province, the largest but least developed of Pakistan's four.

Separatist gunmen shot and killed at least 22 people in southwest Pakistan on August 26 in an attack that singled out ethnic Punjabis, government officials said.

Dozens of militants carried out the shootings early Monday in the district of Musakhail in impoverished Balochistan province, where security forces are battling sectarian, ethnic and separatist violence.

Reuters