KARACHI, April 27, 2022 (BSS/AFP) - A Pakistan separatist group warned Wednesday of more deadly attacks on Chinese targets, a day after a woman suicide bomber killed four people -- including three teachers posted from Beijing.

The Baloch Liberation Army -- one of several groups fighting for independence in Pakistan's biggest province -- claimed responsibility for Tuesday's blast, saying it was the first time a woman had "self sacrificed" for the group.

Chinese nationals and interests have regularly been targeted by separatists in Balochistan, where Beijing is involved in lucrative mining and energy projects.

"Hundreds of highly trained male and female members of the Baloch Liberation Army's Majeed Brigade are ready to carry out deadly attacks in any part of Balochistan and Pakistan," spokesman Jeeyand Baloch said in a statement published in English.

He threatened Beijing with "even harsher" attacks unless the neighbouring country halted its "exploitation projects" and "occupying of the Pakistani state".

Three Chinese teachers and a Pakistani driver were killed near the gate of the Confucius Institute at Karachi University, when the bomber detonated explosives next to their minibus.

A security official at the university told AFP he had previously raised concerns about the safety of 15 Chinese staff on the campus.

"Reports emerged in February that an attack might be carried out on campus," the source, who asked not be named, told AFP.

The bomber was named as 30-year-old Shaari Baloch, a married mother of an eight-year-old girl and four-year-old boy, the BLA said, adding that she was a science teacher studying for a master's degree.

Police confirmed the details.

Suicide attacks by women are very rare in Pakistan, reported only four times in recent years.

China's Ministry of Foreign Affairs urged Pakistan to ensure the safety of all Chinese citizens and interests in the country and to launch a full investigation.

It also advised citizens to "take strict precautions, and do not go out unless necessary".

China is upgrading energy links and infrastructure as part of a $54 billion programme known as the China-Pakistan Economic Corridor, with both nations wary of security threats to the projects.

In April 2021 a suicide bomb attack at a luxury hotel hosting the Chinese ambassador in Quetta, the provincial capital of Balochistan, killed four and wounded dozens.

The ambassador was unhurt in that attack, which was claimed by the Pakistan Taliban.

In July last year, a bus carrying engineers to a construction site near a dam in northwestern Pakistan was hit by a bomb, killing 13 people including nine Chinese workers.

The attack, which went unclaimed, frayed relations between Islamabad and Beijing, and Pakistan later paid millions in compensation to the families of the Chinese workers killed.