UN spokesperson Michele Montas said the world body could not act in the absence of a request from the Pakistani government seeking UN's help in the probe.

The UN could not take any action on the statements made by Bhutto's husband Asif Ali Zardari, she said. Zardari had demanded a UN investigation along the lines of the probe into the killing of Lebanese premier Rafiq Hariri.

"In case of Hariri's murder, the request was received from the Lebanese government," Montas told a press briefing.

Asked whether the request would have to come from President Pervez Musharraf himself, she said the executive branch of the government has to seek the inquiry.

However, she declined to answer whether the Secretary General himself could take action on the request or it needs to be referred to the Security Council. "That would depend on the nature of the request," she said.

Asked why Musharraf would ask for an independent inquiry as fingers have been pointed towards his government, she refused to give a direct reply saying the request for UN's involvement has to come from the Pakistani government.

"This is an intergovernmental organisation, as you know, and this is the way things have to be done. There cannot be any other body to ask. There can be pressure on a Government to ask for this type of assistance, but it (the request) has to come from the Government," the UN spokesperson said.

Montas replied in the negative when asked whether any other government could seek establishment of an independent panel of inquiry for Pakistan.

"We have to get the request first on what specifically they will ask for. I cannot answer a hypothetical question.

They haven't asked specifically for us to send someone to help or for a task force to help with an investigation. If we don't have that request, we cannot go on with it. And that request should be specific. We will consider all aspects of the request.

"I cannot give you an answer beforehand. That's impossible," she told reporters who repeatedly asked what other course was open if Musharraf does not seek international inquiry.

Musharraf last night announced that he has sought the help of Britain's elite Scotland Yard in investigations into Bhutto's murder.