Musharraf told reporters the definitive cause of opposition leader Bhutto's death is still not known, a day after he requested assistance with the investigation from Scotland Yard.
"We needed more experience, maybe more forensic and technical experience that our people don't have," Musharraf said.
Bhutto was killed during a suicide bombing and gun attack after a rally last week. An initial government report found that the shooter missed Bhutto, who was waving to supporters through her vehicle's sun roof, and that she died from cracking her skull on the roof as she fell to dodge the shots.
Bhutto's Pakistan People's Party has ridiculed that report and demanded a United Nations investigation into her death. Many of her supporters have placed blame on Musharraf and the government's security agencies, either accusing them of direct involvement or failure to provide protection.
Musharraf denied that Bhutto was not given suitable security, saying she had the police superintendent of her choice in charge of security, four vehicles, 30 officers, and 1,000 more police at the rally.
"The (security) lapse was not on the government side," he said. "Who is to blame for her coming out of the vehicle?"
He did acknowledge reports that the crime scene was hosed down, possibly resulting in the loss of evidence, shortly after the murder.
"I am sure that they did not do it with an intention of hiding some secrets or that the intelligence agencies instructed them to hide secrets," Musharraf said in response.
In the aftermath of Bhutto's assassination riots in Pakistan's main cities killed at least 58 people. Pakistan's election commission delayed the scheduled election for six weeks, a move that Bhutto supporters say was meant to strip the PPP of any sympathy support it might have garnered.
The Brussels-based International Crisis Group research institute released a report on the assassination warning that if Musharraf does not step down by the election, Pakistan could descend into civil war.
"Unless Musharraf steps down, tensions will worsen and the international community could face the nightmare of a nuclear-armed, Muslim country descending into civil war," the group's Asia director, Robert Templer, said in a statement accompanying the report.
The group called on the United States to recognize Musharraf as "a serious liability, seen as complicit in the death of the popular politician".