Three bomb explosions in Pakistan's business capital of Karachi overnight killed four people and injured 55 others, police said Sunday, dpa reported.
The latest in a string of attacks ahead of the May 11 general elections targeted two main political groups opposed by Taliban militants for their anti-insurgency stance.
Police officer Mohammed Zohaib told dpa a bomb exploded late Saturday near an office of the Muttahida Qaumi Movement (MQM), a dominant party in the city of more than 18 million people.
"One person was killed in the blast, which was followed by a relatively low-intensity explosion outside a nearby Shiite mosque," Zohaib said.
The two blasts occurring minutes apart injured 39 people, he said.
The MQM, which represents Urdu-speaking people who migrated from India after the end of British colonial rule in 1947, shut scores of its local offices earlier this week after a bomb attack killed five of its supporters Thursday.
Also on Saturday night, a bomb ripped through a gathering of the previous ruling Pakistan People's Party in Karachi's Lyari neighbourhood, killing three people and injuring 16 others, Zohaib said.
No group claimed responsibility for the blasts. The Pakistani Taliban have threatened to strike the two parties as well as another secular group, the Awami National Party. Attacks have been carried out on all three.