A suspected suicide bomber has killed at least 133 people in a procession welcoming home ex-Pakistani prime minister Benazir Bhutto.Two explosions in quick succession rocked Ms Bhutto's motorcade. Police believe the bomber threw a grenade before blowing himself up.Interior ministry secretary Syed Kamal Shah said the blasts had also wounded 290 people.The 54-year-old was unhurt in the attack and was quickly escorted away from the truck that had been carrying her from the airport through streets crowded with hundreds of thousands of well-wishers.Karachi police chief Azhar Farooqui said: "Ms Bhutto is safe and she has been taken to her residence."There was no claim of responsibility for one of the deadliest attacks in Pakistan's history.Militants linked to al-Qaeda, angered by Ms Bhutto's support for the US war on terrorism, had this week threatened to assassinate her.Interior Ministry Secretary Syed Kamal Shah said 133 people had been killed and 290 wounded, adding: "The initial investigations suggest it was a suicide bombing."Ms Bhutto was travelling in a platform-mounted truck. Police in vehicles escorting her, reporters and her supporters were among the casualties."The target was the truck," Mr Farooqui said.Eyewitness Athar Hussain, who was slightly hurt in the attack, said "a ball of fire" burst into the air. He then rushed towards the scene.He said: "There was another blast and it was more powerful, then I knew it was a bomb attack. Bodies were scattered all over and wounded were crying for help."The attack took place shortly after midnight, more than ten hours after Ms Bhutto had arrived from Dubai. A city-centre rally she was due to address was cancelled.About 20,000 security personnel had been deployed to protect Ms Bhutto but the provincial governor said in view of the "real threats", authorities had urged her party to wind up the procession faster."Unfortunately, the terrorists got their opportunity," governor Ishrat-ul-Ibad said.Dressed in a green tunic, her head covered with a white scarf, Ms Bhutto had for hours stood in the open on top of the truck, ignoring police advice to stay behind bullet proof glass, as it edged through crowds waving party flags.Ms Bhutto appeared to have had forebodings of an attempt on her life, saying before the attack:"They might try to assassinate me. I have prepared my family and my loved ones for any possibility."President Pervez Musharraf said in a statement the attack was "a conspiracy against democracy".© Independent Television News Limited 2007. All rights reserved.