The elections, now due on February 18, are to elect members of the lower house of parliament, from where a new prime minister and government will be drawn to govern in cooperation with Musharraf, and of assemblies in Pakistan's four provinces.
Bhutto's Pakistan People's Party has dismissed the official account of her killing and called for a U.N. investigation.
It has also said it has no faith in the investigation.
"The Scotland Yard team had only been asked to probe the cause of death and not the perpetrators, financiers, executioners or organisers of the conspiracy," the party said.
Bhutto wrote a letter to Musharraf before she returned from eight years of self-exile in October, naming four people, including one of his political allies and the head of a security agency, that she said should be investigated if anything happened to her.
Asked last week if those people would be questioned, Musharraf said investigators would not be allowed to conduct a "wild goose chase."
Interior Ministry spokesman Javed Iqbal Cheema said the British team was independent and not being restricted.
"They're moving from the criminal scene to the criminals ... in a very systematic manner," Cheema told reporters.
The Interior Ministry said Bhutto was killed when the force of the blast smashed her head into a lever on her car's sunroof, fracturing her skull. Her party said she was shot.
Video footage showed a clean-shaven young man in sunglasses firing a pistol at Bhutto as she stood through the sunroof.
Another man photographed in the crowd with a white shawl over his head shortly before the attack was believe to be the suicide bomber, a television station said.
On Sunday, CBS News quoted Musharraf as conceding that Bhutto might have been shot.
