Hillary Clinton, the US Secretary of State, has accused Pakistani government officials of knowing where Osama bin Laden and leaders of the Afghan Taliban are hiding.

Western officials have repeatedly questioned the determination of Pakistan to tackle militants, a problem which has taken on added significance following the arrest of Faisal Shahzad, accused of trying to detonate a bomb in Times Square.

American officials believe his plot was backed by the Pakistan Taliban increasing pressure on the Islamabad government to strike against the armed groups.

Last week a documentary claimed that bin Laden was alive and well and living in Tehran, where he was learning falconry. However, during a visit to the US, Mahmoud Ahmadinejad, the Iranian president, responded by saying the al-Qaeda leader was in fact hiding in Washington.