Authorities imposed a curfew in a northwestern Pakistani town on Sunday a day after a suicide bomber attacked supporters of assassinated prime minister Benazir Bhutto killing 39 people, an official said.
Saturday's blast in the town of Parachinar near the Afghan border was the most deadly during a campaign for a February 18 general election that nuclear-armed Pakistan's allies hope will help restore stability.
"We haved imposed a curfew to avert any riots. If the situation remains calm then we may relax it," Zaheer-ul-Islam, the district's top government administrator, told Reuters.
Parachinar is the main town of the Kurram tribal region which has seen bloody sectarian clashes between majority Sunni Muslim militants and minority Shi'ites in recent months.
Islam blamed "anti-state elements" for the blast. Another official said a head, suspected to be that of the suicide bomber, had been found.
Islam said authorities had not yet made a decision on whether to go ahead with voting on Monday.
"It depends on the situation," he said.
A doctor at Parachinar's government hospital said 39 people had been killed in the blast and more than 100 were wounded. Many of the wounded were in critical condition and the death toll may rise, he said.
Campaigning for the elections to a new parliament and provincial assemblies has been overshadowed by security fears, especially after opposition leader Bhutto was killed in a gun and suicide bomb attack on December 27.
(Additional reporting by Zeeshan Haider)