"Scotland Yard leading the probe is appropriate and necessary, and we don't see a need for an investigation beyond that at this time. The Pakistanis have just made a decision to ask Scotland Yard to get involved. We welcome that. They have expertise in the area of investigations of this sort," White House spokeswoman Dana Perino said.

Benazir Bhutto's husband Asif Ali Zardari, on Sunday, had demanded for a UN probe into her assassination after the Pakistan government made contradicting versions of how the former premier was murdered.

While terming the involvement of Scotland Yard as a "positive" step, Washington said it is ready to provide any assistance if asked.

"We stand ready to assist, if we are requested to do so. If we can provide technical assistance. And it's within the competence and scope of the investigation to go through all facts and determine who's responsible for this assassination," State Department Spokesman Sean McCormack said.

"And what's most important is that they proceed quickly and in a transparent and comprehensive way, so that the people of Pakistan can get the answers they deserve," Perino said.

However, the officials refused to comment over claims made by Pakistani government over how Bhutto was murdered and said it will not draw any conclusions immediately.

"I'm not going to comment on any particular claims that the Pakistani government has made or the evidence that they have offered up. I certainly have no reason to contradict the claims, but I certainly would not draw any conclusions at this point. Let's wait for that to take place and see what the results are," McCormack said.

Bhutto was assassinated in a suicide attack shortly after she had addressed an election meeting in Rawalpindi on December 27. Her Pakistan People's Party (PPP) has rejected the government's contention that she died of a skull fracture sustained in the suicide attack as "lies".

The US also welcomed the new date set by Pakistan government to hold general elections and said that Washington has been closely working with Islamabad to help it conduct a "free and fair election".

"We've had discussions with them, ongoing. We've been in communication. Secretary Rice has been -- and briefed the president -- in contact with party leaders from the various political parties in Pakistan; been in communication with President Musharraf," Perino said.

"Because the most important thing we can do is to keep Pakistan a stable country, establishing their democracy in a way that can lead them away from violence.