Police said two bombs went off early on Sunday in the suburbs of Quetta, the capital of Baluchistan province, but only shattered window panes in nearby buildings.
   
But a power utility spokesman, Jibrail Khan, confirmed that three pylons had also been blown up in the attacks in Nasirabad district, suspending electricity supply to parts of the province.
   
He added that authorities had restored electricity to most of the area by using an alternative distribution system while a special team had been called from the eastern city of Lahore to repair the damage.
   
The top local official of the district, Sayyid Jamali, told journalists that three towers were razed to the ground and a fourth partially damaged by the explosions.
   
A person identifying himself as a member of the Baluch Liberation Army made a telephone call to the Quetta Press Club later to claim responsibility for all the bombings. 
   
Campaign stepped up

Officials said the attacks caused no casualties, but appeared to be the latest in a stepped up campaign by Baluch tribesmen seeking greater autonomy.
   
In the worst of the recent attacks, as many as 15 people died on 11 January after tribesmen fired rockets at Pakistan's main gas field at Sui, about 400km southeast of Quetta, cutting off supplies for more than a week.
   
Baluchistan has been troubled for decades by a small-scale insurgency by tribesmen, but recent attacks have been unusually intense.
   
The government rushed in additional troops to Baluchistan to protect the vital gas field after the 11 January attack.
   
It has not ruled out military action against tribesmen but at the same time has said it is seeking a political solution to the crisis, which analysts have warned could explode into a full-scale insurgency if not handled carefully.