A suicide bomber has killed 37 people after a meeting of supporters of murdered ex-PM Benazir Bhutto's party, Pakistan's interior ministry says.
The blast took place outside the office of a local politician
The attack, on the last day of campaigning ahead of general elections on Monday, also wounded 90.
It took place in Parachinar, the main town of the tribal region of Kurram in north-west Pakistan.
Violence and vote-rigging fears have marred campaigning for the polls, which were postponed after Mrs Bhutto died.
Mrs Bhutto, the head of the Pakistan People's Party (PPP), was assassinated in Rawalpindi on 27 December.
President Pervez Musharraf said on Saturday that he was confident the elections would be free and fair.
The blast in Parachinar took place as people were gathering outside the office of a local politician - an independent candidate who supports the PPP - after an election meeting had finished.
Eyewitnesses said a car was driven into the crowd and blown up, scattering body parts across the street.
Most of the victims appeared to be PPP members, Mushtaq Hussain, an administrative official in the Kurram area told the Associated Press news agency.
A PPP supporter, Zafar Ali, told AP: "Several of our party members are lying in a pool of blood. We are taking the injured and dumping them into pickup vans to bring them to the hospital."
Mrs Bhutto's successor as party leader, her husband, Asif Ali Zardari, said he condemned the attack "with all the spirit of democracy".
"We still ask people to stay calm because this is again their way of making us lose track and give up the path of democracy," he said.
Correspondents say the area where the attack took place is a volatile border region that has seen rising Islamist militancy in recent months.
In a speech broadcast on state-run television on Saturday, President Musharraf said Pakistan would have a "stable, democratically elected government" which would be used to "ensure a successful fight against terrorism and extremism".
A day earlier, Pakistan's Attorney General Malik Qayyum had rejected allegations that he had said there would be massive rigging in the election.
Human Rights Watch released an audio recording in which a voice, which it said was Mr Qayyum's, could be heard saying "they will massively rig to get their own people to win".
Mr Qayyum, a close ally of President Musharraf, denied making the comments and said the allegations were "a conspiracy against Pakistan".
The president will not be standing in the parliamentary vote on 18 February.
But the former military leader could face a serious challenge to his authority if the vote produces a hostile parliament packed with his opponents.
The PPP says it will consider street protests if it suspects electoral fraud.
President Musharraf has however warned against any such action.
He stepped down as army chief late last year and this election is seen as a key step in Pakistan's transition from military to civilian rule.
Correspondents say fears of violence have kept many Pakistanis from attending rallies during the election campaign.
Security is high in the run-up to Monday's polls, with some 81,000 soldiers deployed to support police across the country.
In separate incidents:
A man equipped with a suicide jacket and explosives was arrested in the southern city of Hyderabad on Saturday, police said.
Police fired tear gas at a rally of about 1,000 people from opposition parties boycotting next week's elections in the south-western town of Quetta on Saturday, police and witnesses said.
The army said a suicide bomber rammed a car into a checkpoint outside an army media centre in the Swat Valley in north-western Pakistan, killing two civilians, the French news agency AFP reported.
Its all a rig not just the votes. This is azbout selecting who THEY WANT. Suicide Bombs???? its all a setup. Conspiracy, Lies, Deceives and cover ups is the aim. They will succeed but for how long is the question??? They know who they are and they will be defeated....
Naveed Rehman, Birmingham, England
The Pakistan people will continue suffering for as long as America supports President Musharraf. Only USA has the key that will unlock the solution to Pakistan's political problems and suffering. Musharraf may pretend to be fighting the "terrorists", but in actual sense he is doing nothing. Musharraf has lost any support he used to command but the USA does not seem to understand the Pakistan people's psych. Many Pakistanis, including Musharraf himself ardently support Al Qaida and the Talibans. President Bush should order "full return to democracy" in Pakistan as he has done in Kenya.
Ondari Okemwa, Alice, South Africa
Mostly shia are killed in the attack.
saeed, parachinar pakistan
Pakistan is not ready for democracy. If the opposition parties have any evidence of vote rigging; they should take the information to law enforcement agencies and a court of law. The option should not be to take to streets and breaking of law and order. The option is within Pakistanis to choose the path of law and order or more heartache. I urge all to stay at home the day after the elections. It will be time for the leadership to lead and respect the verdict.
Syed Askari, Birmingham Uk
The elections in Pakistan, makes no change in present culture of our elite, however, this is a good beginning of new political era. If, our leaders can bring the judges back and independent the media, then i will see Pakistan prosper, otherwise, i am pessimistic about Pakistan
Hasan , Karachi - Pakistan
It seems that election results will be tailored by the Mushraf,but I will perform my duty by casting my vote,will vote for ANP,being a secular and democratic party.
Agha Bakhtiar Ali, Peshawar
i would have definitely voted for ppp if benazir bhutto was alive today,as like many pakistani's i really felt she had a genuine desire and intentions to help pakistan at this crucial moment in our history when we are facing both internal and external issues.Now that she is not there anymore,i am not too sure if i am voting.
I ask a simple a question, Why only leaders of PPP are killed in Pakistan in an unnatural manner. Of course their are leaders from Balochistan too who have same fate. But why this limited to Bhutto's and Balochis. When a murder is committed somebody always gains out of it. Who gains, I do not know, But who loses I know that is people of Pakistan, all those poor and downtrodden who attached hopes with Bhuttos. I will vote for PPP, its the only party have roots in the people.
Haseeb Bhatti, Sargodha, Pakistan
I want to see Such kind of Government who will give only and only justice that kind of government only can survive because our country has a major problem is injustice,so regarding election all kind of leaders are promising to theirs voters that they will give this and that but my observation about all present leaders that are going to fight election after two days but unfortunately I cant see even one man as a good leader at this time in Pakistan.Now a time i am in Saudi Arabia but i want to serve the people by fighting for their justice with these all leaders in Pakistan.I want to give my vote those poor people all over the pakistan who are suffering by the cruelties of those rich persons who are going to fight elections.
Amir Mahmood, Jhang,Pakistan