Islamabad: A suicide bomber blew himself up near the venue of a political rally at Battagram in northwest Pakistan on Monday, killing seven persons and injuring 25 others, police said.

The bomber struck as workers of the PML-Q party, which is part of the ruling coalition at the centre, were preparing for a rally to be addressed by senior party leader and former Federal Minister Amir Muqam.

The bomber detonated his explosive vest after he was stopped by policemen deployed to guard the venue of the meeting.

Two policemen and two women were among the seven persons killed by the blast, police officials said.

Twenty-five people, including women and children, were injured. Officials described the condition of eight of them as serious.

The blast hit the nearby office of the water and power utility, witnesses said. Initial reports had said that three policemen were killed in the attack.

PML-Q workers said senior leader Amir Muqam was safe as he was not at the venue at the time of the blast. The rally was cancelled following the blast.

The main market in Battagram was closed to protest the attack. No group claimed responsibility for the attack though such suicide bombings are usually blamed on the Pakistani Taliban.