A remote-controlled bomb exploded on a railway line in Nasirabad in the province of Balochistan.

The United States on Tuesday designated those fighting Pakistani rule in Balochistan as terrorists after it carried out deadly attacks targeting Chinese interests.

The State Department said it was classifying the Balochistan Liberation Army as a global terrorist group, making it a crime for anyone in the United States to assist the terrorists and freezing any US assets they may have.

The Balochistan Liberation Army "is an armed separatist group that targets security forces and civilians, mainly in ethnic Baloch areas of Pakistan," the State Department said in its designation.

Pakistan has been fighting insurgents in the southwestern region since 2004, with the terrorists recently finding a new focus in rallying against China's investment that is part of its major Belt and Road initiative.

The Balochistan Liberation Army has targeted China in Pakistan multiple times, including a brazen daylight attack on the Chinese consulate in Karachi that killed four people in November.

In May, five people including a soldier were killed after gunmen stormed the only five-star hotel in Gwadar, the port city which Pakistan is hoping to develop into a major commercial hub.

Claiming responsibility for the hotel attack, the Balochistan Liberation Army warned China to stop its "exploitative projects in Balochistan" and not to support the "genocide of Baloch people," threatening further attacks.

Pakistan has been accused of widespread human rights violations in its crackdown in Balochistan.

Pakistan denies wrongdoing and accuses its historic rival India of fomenting the insurgency, an assertion scoffed at by New Delhi.

The US designation of the group comes despite vocal concerns by Washington over the Belt and Road initiative, with Washington accusing China of imposing debt traps on developing nations.