Suspected tribal rebels blew up a key pipeline in Balochistan on Tuesday, leaving tens of thousands of people without gas, officials said. The pre-dawn blast suspended natural gas supplies to provincial capital Quetta, as well as to the Kalat, Mastung, Ziarat and Pishin districts, a gas company official said on condition of anonymity. Repair work has begun on the ruptured section of the pipeline at Dasht, near Quetta, and supplies will hopefully be restored later Tuesday, the official added.The attack was the third of its kind since Monday when two other pipelines were blown up elsewhere in Balochistan. Rebels also attacked a passenger train with rockets on Thursday but caused no casualties.