A power pylon was toppled by the first bomb on Monday at Killi Kishungi in Naushki district, 130km southwest of Quetta, said electricity company spokesman Gibrael Khan. Hundreds of homes in the area were plunged into darkness, he added.

Another bomb ripped through the shutters of a steel workshop in Naushki, a local police official said on Tuesday.

The third bomb exploded near the regional office of the army-led Anti-Narcotics Force in the town of Turbat, 600km southwest of Quetta, but caused no damage, said local police official Habibullah.

Nobody claimed responsibility for the blasts. Officials have blamed nationalist tribesmen demanding autonomy and greater benefits from the region's natural resources, for the recent string of bomb blasts and rocket attacks.

Resource-rich but poverty-stricken Baluchistan has seen a rise in violence since January when rebels launched a deadly rocket barrage on a major gas plant, in revenge for the alleged rape of a female doctor there by soldiers.

Thousands of troops moved into the province after the attack, which killed eight people.