A cordon of police surrounded the park where Bhutto spoke, yet her attacker was able to get to the rear gate, where he shot her as she was leaving and then detonated himself, witnesses said.
"How could they enter with so much of a police cordon. I am surprised," Gul said.
A Washington-based friend of Bhutto's, Mark Siegel, told CNN that the former prime minister had been "very concerned that she was not getting the security that she had asked for," including devices used to jam mobile phone signals.
"She had asked for special tinted cars, she had asked for four vehicles to surround her at all times," Siegel said. "All of that was denied to her."
Gul asserted that a suicide bomber could not have carried out the attack without having been forewarned of Bhutto's movements with a mobile phone or other device.
Bhutto had complained after the October assassination attempt in the city of Karachi that jamming devices had not been working, Gul said.
"Why were the jammers not working? She had been begging the government after the attack in Karachi saying the jammers were faulty then," he said. "I know that these things could not occur if the jammers are working."
"I think it is convenient to put the blame on al-Qaeda. But there are other possibilities and they have to be examined," Gul said, without offering specifics.
Gul strongly opposes the US-backed campaign against Islamic militants and has labeled himself the jihadists' only public supporter.
In an interview last month, a former district leader of Hezb-ul Mujahidin said some members of Pakistan's intelligence services resented the idea of a woman leading a Muslim nation, as well as Bhutto's denunciation of militant Muslims. Hezb-ul Mujahidin is believed to be heavily funded by Pakistani intelligence to fight in Indian-controlled Kashmir.
"In the Pakistani [secret] agencies and in the army there are so many people who are not secular, who are fundamentalists and will help a suicide bomber to carry out his job," said the former district leader, Saifullah, who uses just one name.
A former Taliban intelligence official, Mullah Ehsanullah, said earlier this year that there were more than 500 men training as suicide bombers in 50 sites across Pakistan and Afghanistan.
These camps he said, are run by al-Qaeda and include Pakistani jihadists and Arab militants.
US officials in Washington said they were trying to determine who might have carried out the attack.
FBI spokesman Richard Kolko said: "The FBI continues to work with our US intelligence community partners reviewing the al-Qaeda claims for responsibility for any intelligence value. The validity of those claims are undetermined."
The statement came after a law enforcement official said that a national FBI and Homeland Security bulletin to law enforcement agencies cited Web sites as saying al-Qaeda had claimed responsibility.
RSS