The state-run Associated Press of Pakistan reported the attack occurred near the village of Eidak at a rally for the opposition Awami National Party.

CNN reported it was the third time a rally by the leftist nationalist Pashtun party has been targeted in less than a week as the country gets ready for parliamentary elections next Monday.

Last Saturday, a suicide bomber killed more than a dozen people at an ANP rally in northwestern Pakistan. Last Wednesday, the party's vice president was killed in Karachi, the report said.

Violence has escalated sharply in recent months in Pakistan's tribal regions where the Taliban and al-Qaida have regrouped and from where they plan their attacks on coalition forces in neighboring Afghanistan.