Rail authorities said three explosions ripped off a 36-foot (11.5-metre) portion of track outside Quetta, the capital of Baluchistan province, a region where tribal rebels have been waging an insurgency for years.

The train, heading for the Iranian border town of Zahdan, had already left Quetta but was stopped soon after its departure as railway workers detected a bomb 35km down the track, official Shoaib Khan told AFP.

As bomb experts defused the first device three other explosions occurred a short distance away destroying the track, Khan said.

Officials said the bombs were intended to target the train, which only had around 30 people including staff members aboard.