Two Chinese nationals have been killed and at least ten people injured after an explosion near Jinnah International Airport in Karachi, Pakistan.

The Chinese embassy in Pakistan said there were “some local casualties” in what it described as a “terrorist attack”, though the overall death toll is still unclear.

The embassy added that the explosion targeted a convoy of Chinese engineers working on a power project in the country’s Sindh province.

The separatist Balochistan Liberation Army (BLA), which has in recent years carried out attacks on Chinese nationals involved in projects, has claimed responsibility for the attack.

In a statement released on Monday, the militant group said it had “targeted a high-level convoy of Chinese engineers and investors” arriving from Karachi airport.

The attack was carried out using a “vehicle-borne improvised explosive device”, Reuters quoted the BLA as saying.

The explosion happened around 23:00 local time (17:00 GMT).

The Chinese embassy said that the engineers were part of the Chinese-funded enterprise Port Qasim Power Generation Co Ltd, which aims to build two coal power plants at Port Qasim, near Karachi.

The plant is part of the China-Pakistan economic corridor, which is also funding a number of infrastructure and energy projects in Pakistan’s Balochistan province, which has a rich supply of natural resources, including gas and minerals.

The BLA along with other ethnic Baloch groups has fought a long-running insurgency for a separate homeland.

It has regularly targeted Chinese nationals in the region, claiming ethnic Baloch residents were not receiving their share of wealth extracted from foreign investors.

The Chinese embassy on Monday reminded its citizens and Chinese enterprises in Pakistan to be vigilant and to “do their best to take safety precautions”. The embassy added that it will thoroughly investigate the attack and “severely punish the murderer”.

There has also been heightened security in Pakistan as it prepares to host the leaders’ summit of the Shanghai Cooperation Organisation (SCO).

The blast was reportedly heard in various areas around the city, with footage from local media showing thick smoke and cars set alight.

Sindh Home Minister Ziaul Hasan Lanjar said that the explosion was likely to be have been caused by a suspected improvised explosive device (IED).

Pictures online show security officials and firefighters investigating the explosion site, where several vehicles have been charred by the blast.

A police surgeon, Dr Summaiya told Dawn news: “Ten injured persons, including one in critical condition, have been brought the Jinnah Postgraduate Medical College (JPMC).”

She added the injured included a police constable and a woman.

A statement posted on X from Sindh’s Interior Minister’s office said that a “tanker truck” had exploded on Airport Road and said the minister was in contact with the Malir Senior Superintendent of Police (SSP) regarding the incident.

“We need to ascertain the facts,” the statement said.

Jinnah International Airport is functioning as usual today.

The BLA had claimed responsibility for past assaults on a Pakistani naval airbase near the Gwadar port, another main feature of the China-Pakistan economic corridor.

In April 2022, it killed three Chinese tutors and a Pakistani driver in a suicide bombing near Karachi University’s Confucius Institute.