Describing the assassination of Benazir Bhutto as an "utter shock", Pakistan President Pervez Musharraf has denied any hand in the killing of the former Prime Minister, and said nobody should be assigned any blame until investigations are over.In an interview on CBS News' Sixty Minutes, Musharraf maintained that he had personally told Bhutto that she was under threat and that under the circumstances, the Pakistan People's Party leader should not have done the things she did on that fateful day in December."This is unfortunately a very baseless allegation," Musharraf said of the possibility that he had a hand in the killing of Bhutto. "Nobody has a right to blame anyone for killing anyone unless they have the proof," he said."Why would I be informing her about all these intelligence reports that we have against her, the threat to her? Why would I be doing that?... I can't prove it legally, I can't prove my innocence legally. But I can prove it only through what I stand for as a person," he said, adding "There's no real protection against a suicide bomber."Musharraf blamed al-Qaeda for Bhutto's assassination, particularly local extremist Beitullah Mehsud, who operates out of Pakistan's lawless tribal region.Regarding al-Qaeda supremo Osama bin Laden, Musharraf said his administration was not particularly looking for him as there was "no proof" he was in Pakistan."We are fighting extremism... We have arrested or eliminated about 700 al-Qaeda leaders. Only Pakistan has done it. Who else, which other country has done this?" he said.When countered by his questioner that no other country had bin Laden, Musharraf responded, "No, I challenge - I don't accept that at all. There is no proof whatsoever that he is here in Pakistan."COMPLETE COVERAGE: TURMOIL IN PAKISTAN