A bomb killed at least 20 people and injured 40 others Friday during a rally in Pakistan's restive Balochistan province, in the day's second attack on a political event ahead of the July 25 election.

"Twenty people were killed in the blast and we fear this toll may rise," Agha Umar Bungalzai, provincial home minister, told AFP, adding that more than 40 were wounded in Mastung town, near the provincial capital of Quetta.

Bungalzai also confirmed the explosion killed Siraj Raisani, who was running for a provincial seat with Balochistan Awami Party (BAP).

"Mir Siraj Raisani succumbed to wounds while he was being shifted to Quetta," he added.

Raisani was younger brother of former provincial chief minister Mir Aslam Raisani.