Washington ? The United States provided a steady stream of intelligence to Benazir Bhutto about threats against her before the former Pakistani prime minister was assassinated and advised her aides on how to boost security, although key suggestions appear to have gone unheeded, U.S. officials said Monday.

Senior U.S. diplomats had multiple conversations, including at least two private face-to-face meetings, with top members of Bhutto’s Pakistan People’s Party to discuss threats on the Pakistani opposition leader’s life and review her security arrangements after a suicide bombing marred her initial return to Pakistan from exile in October, the officials told The Associated Press.

The intelligence was also shared with the Pakistani government, the officials said.

Much of what was passed on dealt with general threats from Taliban extremists and al-Qaida sympathizers and “was not actionable information.”

The officials said Bhutto and her aides were concerned, particularly after the October attack, but were adamant that in the absence of a specific and credible threat there would be few, if any, changes to her campaign schedule ahead of parliamentary elections.

“She knew people were trying to assassinate her,” said an intelligence official. “We don’t hold information back on possible attacks on foreign leaders and foreign countries.” The official added, however, that while the U.S. could share the information, “it’s up to (the recipient) how they want to take action.”

The Pakistani government has said that Bhutto died not from bullet or shrapnel wounds but from injuries sustained while hitting her head on her vehicle’s sunroof during Thursday’s attack.

A dispute over the explanation of how she died intensified after a medical report didn’t state what had caused her injuries and a video obtained by Britain’s Channel 4 television showed a man firing a pistol at Bhutto from just feet away as she poked her head out of the sunroof. In the footage, her hair and shawl jerk upward and she falls into the vehicle just before an explosion. No police are seen trying to push the crowd away.

The Bush administration has quietly joined calls for Pakistan to allow international experts to join the probe into Bhutto’s Dec. 27 slaying. The officials said they expected an announcement soon that investigators from Britain’s Scotland Yard would be asked to play a significant role.

Pakistan’s ambassador to the United States, Mahmud Ali Durrani, said Monday that his government would welcome outside experts to help investigate the assassination, according to The New York Times.

“Pakistan is open to international expertise, international support and international help because it’s in our interests,” Durrani told the newspaper in a story posted late Monday on its Web site.