WASHINGTON/ABBOTTABAD: Pakistan on Tuesday denied it gave shelter to Osama Bin Laden but the White House vowed to “get to the bottom” of whether Pakistani authorities helped the Al-Qaeda leader elude a long manhunt before he was killed in a US raid. Washington kept Pakistani officials in the dark about the special forces assault near Islamabad, fearing they might “alert the targets” and jeopardize the mission, which ended with Bin Laden's death Monday, CIA Director Leon Panetta told Time magazine. The revelation that Bin Laden had holed up in a fortified compound in the military garrison town of Abbottabad, possibly for five to six years, prompted many US lawmakers to demand a review of the billions of dollars in aid Washington gives to nuclear-armed Pakistan. Pakistani President Asif Ali Zardari, issuing his first response to questions about how the world's most-wanted militant was able to live undetected for so long near the capital Islamabad, did little to dispel suspicions. “Some in the US press have suggested that Pakistan lacked vitality in its pursuit of terrorism, or worse yet that we were disingenuous and actually protected the terrorists we claimed to be pursuing,” Zardari wrote in the Washington Post. “Such baseless speculation ... doesn't reflect fact.” It was the first substantive public comment by any Pakistani leader on the airborne raid that killed the Al-Qaeda leader, who had become the face of militancy since masterminding the Sept. 11, 2001 attacks on the United States. Pakistan has come under enormous international scrutiny since Bin Laden was killed, with questions over whether its military and intelligence agencies were too incompetent to catch him or knew all along where he was hiding, and even whether they had been complicit. “It would be premature to rule out the possibility that there were some individuals inside of Pakistan, including within the official Pakistani establishment, who might have been aware of this,” White House counterterrorism chief John Brennan told National Public Radio. “We're not accusing anybody at this point, but we want to make sure we get to the bottom of this,” he said. Reflecting a US-Pakistani alliance strained by years of mistrust, Islamabad was not told about the raid until after all US aircraft were out of Pakistani airspace. While Islamabad hailed the killing of Bin Laden as an important milestone in the fight against terrorism, Pakistan's foreign ministry expressed “deep concerns” that the operation was carried out without informing it in advance. Pakistan, which for years has said it did not know Bin Laden's whereabouts, said it had been sharing information about the targeted compound with the CIA since 2009. Facing pressure to produce visual confirmation of Bin Laden demise, Brennan said the United States was considering releasing photos and video taken during the raid as proof Bin Laden was dead, but would only do so in a “thoughtful manner”. The Afghan Taliban challenged the truth of Bin Laden's death, saying Washington had not provided “acceptable evidence to back up their claim” that he had been killed. New details emerged about the deadly assault. Bin Laden was unarmed when US forces stormed the compound and engaged in a firefight there, but White House spokesman Jay Carney insisted the Al-Qaeda leader did resist – though he would not say how. He said Bin Laden's wife rushed a commando and was shot in the leg but not killed, contrary to what a White House official said earlier about her dying while acting as his shield.