At least 18 people have died after a powerful explosion hit an opposition election rally in north-western Pakistan, the interior ministry says.
Victims of the bomb attack were carried to safety
The suspected suicide attack happened in Charsadda, in the North West Frontier Province.
The blast occurred at a rally of the Awami National Party (ANP), a secular Pashtun party, as campaigning began for elections due on 18 February.
Correspondents say suspicions are likely to fall on Islamist groups.
"Apparently it was a suicide attack," interior ministry spokesman Javed Iqbal Cheema told Reuters news agency.
The ANP is seen as an anti-Islamist force, and suspicion for the blast is likely to fall on al-Qaeda or jihadist elements, the BBC's Barbara Plett says.
North West Frontier province, bordering Afghanistan, is a hotbed of Taleban militancy and has been the scene of frequent unrest.
On Thursday, Fazal-ur-Rehman Atakhail, a senior member of the party, was shot dead by an unknown assailant whilst travelling in his car in Karachi, triggering widespread protests.
The upcoming elections are seen as a test of the democratic credentials of President Pervez Musharraf, who recently stepped down as military leader.
In the south of Pakistan, tens of thousands of supporters of the late opposition leader, Benazir Bhutto, gathered for her Pakistan People's Party's first campaign rally since her assassination in December.
Mrs Bhutto's assassination prompted the postponement of the election, which was originally scheduled to take place in January.
In a separate development, police in Islamabad have used tear gas and water cannon to stop hundreds of lawyers reaching the home of the former chief justice, Iftikhar Muhammad Chaudhry, who was sacked by Mr Musharraf last November.
He is still under house arrest in the capital, despite the lifting of the state of emergency in mid-December.
Pakistan's Bar Council has said lawyers will boycott the courts as part of the campaign to have senior judges sacked by Mr Musharraf reinstated.