Terrorists in explosive vests have reportedly threatened Pakistan train passengers' lives if officials refuse to release imprisoned militants.

Almost 350 hostages were rescued and 27 were killed after the Baloch Liberation Army hijacked a train in Pakistan's Balochistan province.

Twenty-one passengers, four soldiers and 33 terrorists were killed after heavily armed terrorists attacked a passenger train and held scores hostage in the country's southwestern Balochistan province, the Inter-Services Public Relations (ISPR), the media wing of the Pakistan Army, said in a statement late Wednesday night.

Nearly 200 have been freed but the status of other passengers remains unclear as security forces continue to battle separatist militants.

Citing security sources, state broadcaster PTV reported militants were holding passengers hostage in the train, which was trapped inside a tunnel. A clearance operation was ongoing. The Baloch Liberation Army,