At least four killed in Pakistan bomb blast

At least four political workers were killed and 13 injured in a bomb blast in Pakistan's restive south-western province of Balochistan, officials said late on Thursday.

The explosion occurred as the workers from an Islamist party were leaving a venue after a conference in the provincial capital of Quetta, which is home to several insurgent groups.

"At least four political workers were killed and 13 others injured," said Fida Hassan Shah, a senior police official.

"It was an improvised explosive device and some 1.5 kilograms of explosive was used."

Javed Akhtar, an official with Sandeman Provincial Hospital Quetta, confirmed the death toll.

Pakistan is fighting several low-level insurgencies in the impoverished province, waged by religious, separatist and sectarian groups.

No group has yet claimed responsibility for the attack, which the Chief Minister of the province, Mir Abdul Qudoos Bizenjo, called an "act of terrorism".

Balochistan is Pakistan's largest and poorest province, despite being rich in natural resources.

Billions of dollars have been flowing into the region through the China-Pakistan Economic Corridor, but locals say most new jobs from investments went to outsiders.