Some saboteurs made an attempt on Wednesday to blow up a 500KV high transmission line near NDT in Jamshoro, reported 24NewsHD TV channel.
The blast, however, damaged two electricity pylons.
Police have cordoned off the area and called in a bomb disposal squad.
As per the reports, no loss of life has been reported during the blast.
The bomb device which went off was homemade.
Jamshoro SSP Imran Qureshi said that two electric poles were affected by the explosion.
Reporter Zohaib Solangi