The death toll from a bombing at a railway station in troubled south western Pakistan has risen to at least 24, officials said.

The attack on Saturday also left more than 50 others wounded, some critically. Police said about a dozen soldiers and six railway employees were among the dead.

The bomb exploded when nearly 100 passengers were waiting for a train to the garrison city of Rawalpindi from Quetta, the capital of the restive Balochistan province, said senior police officer Mohammad Baloch.

The Balochistan Liberation Army (BLA), a separatist group, said it was behind the attack in a statement, saying a suicide bomber targeted troops present at the railway station.

The site of a bomb explosion at a railway station in Quetta, south western Pakistan (Arshad Butt/AP)

Government spokesman Shahid Rind said the bombing seemed to have been a suicide attack, but an investigation was still ongoing to confirm the BLA’s claim

TV footage showed the steel structure of the platform’s roof blown apart and a tea stall destroyed as luggage littered the scene.

Quetta police official Ayesha Faiz said some of the critically wounded passengers died in hospital.

Denouncing the bombing in a statement, Prime Minister Shehbaz Sharif said those who orchestrated the attack “will pay a very heavy price for it”.

He said security forces were determined to eliminate “the menace of terrorism”.

The oil and mineral-rich Balochistan is Pakistan’s largest, but also least populated province. It is also a hub for the country’s ethnic Baloch minority whose members say they face discrimination and exploitation by the central government.

Along with separatist groups, Islamic militants also operate in the province.

The outlawed BLA has long waged an insurgency seeking independence from Islamabad.

The group often targets security forces and foreigners, especially Chinese nationals who are in Pakistan as part of Beijing’s multi-billion dollar Belt and Road Initiative, which is building major infrastructure projects.

Last month, BLA claimed responsibility for a suicide bombing that targeted a convoy with Chinese nationals outside Karachi airport, killing two.

Since then, Beijing has asked Pakistan to ensure the safety of its citizens working on multiple projects in Balochistan and other parts of the country.