Three people were killed and 35 others wounded in twin bomb blasts near a local party office in the southern city of Karachi late Saturday, police said, ahead of next week's historic elections.
The two bombs exploded within 20 minutes of each other near an office of the Muttahida Qaumi Movement (MQM) in the middle class neighbourhood of Azizabad, senior police official Saleem Akhtar Siddiqui told AFP.
"We can confirm that three people have died in the twin blasts while 35 have been wounded. The wounded have been admitted to different hospitals," said Suresh Kumar, secretary of the health department of Sindh province.
No MQM workers were identified among the dead and wounded, Siddiqui said.
A spokesman for MQM, Qamar Mansoor, said a rally had been planned in the area hit by the Saturday blasts, but would now be postponed and a day of mourning observed instead.
Pakistan will elect its new government for the next five years in polls on May 11. The election of the national and regional assemblies will mark the first time a civilian government has completed a full term and handed over to another, in a country that has been ruled by the military for half its existence.
Campaigning has been marred by Taliban threats and attacks, which have killed 66 people since April 11, according to an AFP tally.
On Friday, national assembly candidate Saddiq Zaman Khattak was shot dead along with his three-year-old son after praying in a mosque in the city of Karachi.
Khattak was a businessman and a candidate for the Awami National Party (ANP), the leading secular party in Pakistan's ethnic Pashtun northwest.
Earlier on Saturday a candidate running for parliament was injured when his vehicle hit a roadside bomb in the troubled northwest, officials said.
In a separate incident, an election office of the cricketer-turned-politician Imran Khan's Pakistan Tehreek-e-Insaaf (PTI) party was attacked in Peshawar.