US Secretary of State Hillary Clinton has launched a withering attack on the Pakistani authorities over their failure to hunt down al-Qa'ida leaders. The US believes Osama bin Laden and his senior lieutenants are hiding out in the mountains along the Pakistan-Afghanistan border. The area is effectively under the control of local tribal militias and Islamic militants. Pakistan has launched a number of offensives against the militants in recent years, leading to a major upsurge in bombings, assassinations and gun attacks across Pakistan. Mrs Clinton, however, told Pakistani journalists in Lahore that she found it "hard to believe that nobody in your government knows where they [al-Qa'ida leaders] are and couldn't get them if they really wanted to".