Parachinar: Pakistan's Parachinar town was placed under a curfew on Sunday, a day after a suicide bombing killed at least 39 people.
Health officials fear the death toll may rise after many of the more than 100 wounded in the attack remain in critical condition.
The blast on Saturday occurred as supporters of a candidate backed by assassinated prime minister Benazir Bhutto's party were going to the his office after a rally.
The head of the suspected suicide bomber has been found on the blast site in the Kurram region on the Afghan border, an official said.
"We have imposed a curfew to avert any riots. If the situation remains calm then we may relax it," said Zaheer Ul Islam, the district's top government administrator.
Islam blamed "anti-state elements" for the blast and said that authorities had not yet made a decision on whether to go ahead with voting on Monday.
