Media said another 500 people were injured in the two explosions early on Friday in the middle of a huge crowd, near the motorcade of ex-premier Benazir Bhutto, who had returned to the country on Thursday after an eight year absence. The windows of Bhutto's bullet-proof truck were shattered, but she emerged unharmed.
Musharraf discussed the security situation in the country at his private residence in Rawalpindi, near Islamabad, with the heads of security agencies. He also spoke on the phone to Bhutto, who is now at a family residence in Karachi, expressing his shock and sadness over the attack.
Police said the attack, one of the bloodiest in Pakistan's history, was perpetrated by suicide bombers, who let off a grenade before blowing themselves up. A severed head believed to belong to one of the bombers has been found by police, and his identity is being established, according to national TV channels.
Bhutto accused supporters of former military dictator General Zia-ul-Haq of orchestrating the attack. Zia, who overthrew Bhutto's father Prime Minister Zulfikar Ali Bhutto and had him executed in 1979, died in a car crash in 1988.
Speaking at a news conference, she said: "The attack was on what I represent. The attack was on democracy and the very unity and integrity of Pakistan."
Bhutto, who leads the center-left Pakistan People's Party (PPP), served as Pakistan's prime minister on two separate occasions, but both her previous governments were brought down amid corruption allegations and she was forced to flee in 1999, dismissing the allegations as politically motivated.
President Musharraf has declared an amnesty for Bhutto to protect her against the corruption charges, but the Pakistani Supreme Court is set to hear appeals against the amnesty.
The official spokesman for the Russian Foreign Ministry issued a statement condemning the terrorist attack in Karachi.
"While expressing deep sympathy for the families of the victims, Moscow strongly condemns this latest crime against civilians," Mikhail Kamynin said.