At least 12 passengers were killed and more than 30 wounded on Tuesday when militants bombed a train in Pakistan's Baluchistan province, hospital sources and officials said.
The blast came a day after Pakistani security forces said they had killed 30 separatist militants in one of the biggest clashes in months in the gas-rich province.
There was no claim of responsibility for the blast and it was not clear if it was related to the fighting.
The bomb went off on the Rawalpindi-bound Jaffar Express in a carriage reserved for men, in the town of Sibi, 120km south-east of the provincial capital of Quetta.
"Fire engulfed the [carriage] following the blast causing most of the deaths," said a rescue worker. Railways Minister Khawaja Saad Rafique confirmed the death toll.
Government officials did not identify which militant group they believed was responsible.
The low-level separatist insurgency in Baluchistan is one of the chronic security problems undermining stability in Pakistan.
Mired in poverty
The separatists accuse the government of stripping the province's natural resources and leaving its people mired in poverty. They say government-backed death squads routinely abduct, torture and execute ethnic Baluch, accusations echoed by human rights campaigners.
The security forces deny violating human rights.
Insurgents have also targeted civilians, especially Pakistanis from other ethnic groups who have settled in Baluchistan.
The government tightly controls access to the province and it is difficult for foreign journalists to get permission to travel there. &dnash; Reuters