The Obama administration has seen no evidence Pakistan's leadership knew Osama bin Laden was living in that country before his killing, the US national security adviser said today.
"I can tell you directly that - I've not seen evidence that would tell us that the political, the military, or the intelligence leadership had foreknowledge - of bin Laden," Tom Donilon told NBC when asked if Pakistan was guilty of harbouring the al-Qaeda leader.
But he added bin Laden's residence for several years inside a compound in Abbottabad, 60km north of the capital, Islamabad, "needs to be investigated.
"The Pakistanis have said they're going to investigate," Mr Donilon said. "This is a very big issue in Pakistan right now. How could this have happened in Pakistan? We need to investigate it. We need to work with the Pakistanis. And we're pressing the Pakistanis on this investigation."
Mr Donilon, who appeared on a number of Sunday talk shows, told CNN that he expected cooperation from Pakistanis. "We would expect to have access to the things that we need," he said.
He said Pakistani officials also needed to provide US authorities with intelligence they had gathered from the compound where bin Laden was killed, including access to bin Laden's three wives who are in Pakistani custody.
Former vice president Dick Cheney told Fox News that it was important for the United States to maintain good relations with Pakistan. "I have questions, I'd like to know more about it," Mr Cheney said about bin Laden's presence in Pakistan. "But I also think it's important for us to remember we have a broad range of issues that we work with Pakistan together."
Pakistan, heavily dependent on billions of dollars in US aid, is under intense pressure to explain how bin Laden could have spent so many years undetected just a few hours' drive from its intelligence headquarters in the capital.
Pakistani officials said yesterday bin Laden may have lived in Pakistan for more than seven years before he was shot to death by US Navy Seals.
One of bin Laden's widows told Pakistani investigators that he stayed in a village for over years before moving to the nearby garrison town of Abbottabad.
The wife, Amal Ahmed Abdulfattah, said bin Laden and his family had spent five years in Abbottabad.
"Amal (bin Laden's wife) told investigators that they lived in a village in Haripur district for nearly two and a half years before moving to Abbottabad at the end of 2005," one of the security officials said on condition of anonymity.
Abdulfattah, along with two other wives and several children, were among 15 or 16 people detained by Pakistani authorities at the compound after the raid.
The senior US intelligence official said bin Laden's identity had been confirmed after his death in several ways - by a woman at the compound, by facial recognition methods and by matching against a DNA profile with a likelihood of error of only one in 11.8 quadrillion.
Suspicions have deepened that Pakistan's pervasive Inter-Services Intelligence (ISI) spy agency, which has a long history of contacts with militant groups, may have had ties with bin Laden - or that at least some of its agents did. The agency has been described as a state within a state.
Pakistan has dismissed such suggestions and says it has paid the highest price in human life and money supporting the US war on militancy launched after bin Laden's followers staged the September 11th, 2001, attacks on America.
Security officials said Pakistan had launched an investigation into bin Laden's presence in the South Asian country seen as critical to stabilising neighbouring Afghanistan. "It is very serious that bin Laden lived in cities (in Pakistan) ... and we couldn't nail it down fully," said one of the Pakistani officials.