A suicide bomber blew himself up at an opposition election rally in northwestern Pakistan on Saturday, killing at least 20 people and wounding 25, government and party officials said.
The attacker struck as hundreds of people gathered for a meeting of the Awami National Party (ANP), a nationalist ethnic Pashtun party, in the town of Charsadda in the troubled North West Frontier Province, they said.
The bombing has further raised fears for the security of general elections on February 18, which have already been delayed by the assassination of opposition leader Benazir Bhutto at a rally in December.
"According to initial reports 20 people were killed and 25 were injured. One of the injured told me in the hospital that it was a suicide attack but I cannot confirm it officially," provincial health minister Syed Kamal Shah told AFP.
Interior Minister Hamid Nawaz linked the attack to a wave of other bombings blamed on Al-Qaeda and Taliban militants that have claimed more than 70 lives this year.
"Yes, it was most probably a suicide attack. It was close to the stage but none of the ANP leaders there were hurt," Nawaz told AFP. He said that 14 people were dead and 24 injured.
"This is very significant that the ANP rally has been hit... these people are trying to hit at everyone, the threat posed by them is challenging everyone in Pakistan."
"We are beefing security measures because only a little more than a week is left in the elections," he added.
Last year former interior minister Aftab Sherpao survived two suicide attacks in Charsadda that left dozens of people dead, the most recent being in December.
But an ANP spokesman said he believed Pakistani government intelligence agencies were behind the blast, which he confirmed was by a suicide bomber.
"We blame security agencies for the attack. The agencies want to create civil war and want to support dictatorship," spokesman Zahid Khan told AFP.
"The bomber blew himself up very near the stage, the party's provincial candidate was slightly injured. But it was a meeting which was not held in the open, but inside four walls, so how come the bomber was conveniently able to enter?"
The attack comes three days after gunmen on a motorbike shot dead the ANP's vice-president, Fazalur Rehman Atakhel, in the southern city of Karachi, sparking riots by supporters.
Election rallies have been sparse since Bhutto's death in a suicide bomb and gun attack in Rawalpindi on December 27 and after the government issued a "security advisory" for candidates to avoid big gatherings.
President Pervez Musharraf blamed an Al-Qaeda-linked militant commander based in a troubled tribal zone bordering Afghanistan for her killing.
Even the former ruling Pakistan Muslim League-Q, which backs Musharraf, has kept a low profile.
Pakistan earlier on Saturday dismissed a senior US official's assertion that Al-Qaeda and Taliban leaders Osama bin Laden and Mullah Mohammad Omar were operating from its border areas.
"The claim by an unnamed official is baseless," said Foreign Ministry spokesman Mohammad Sadiq, who said Islamabad would take action if the US provided it with intelligence to support the statement.
The US official made the comment at a media briefing in Washington on Friday, as US Chairman of Joint Chiefs of Staff Admiral Mike Mullen was in Pakistan for talks with top military officials believed to focus on counter-terrorism.