The US raid that killed Osama Bin Laden at his secret compound in Pakistan amounted to an "American act of war" against the South Asian country, a government investigation into the operation has found.

Pakistan's Abbottabad Commission, set up to probe the raid and previous efforts to capture the Al-Qaeda leader, delivered a trenchant condemnation of the US decision to unilaterally launch the operation inside Pakistani territory without seeking permission from the government in Islamabad. It painted the United States as an "arrogant" military power disdainful of the rights of other nations, over which it would ride roughshod in pursuit of its security goals.

The commission's report - leaked by Al Jazeera on Monday - denounced the US action as the "greatest humiliation" suffered by Pakistan since 1971, when East Pakistan seceded to form Bangladesh.