After al-Qaeda chief Osama bin Laden was killed by US special forces in Pakistan's garrison town of Abbottabad, his body was kept in a heavy black bag of 300 pounds of iron chain and dropped into the sea, former CIA Director and Defense Secretary Leon Panetta has said.

After Osama was shot dead, Panetta said, as planned the body of the world's most wanted terrorist was transported by marines flying an Osprey to waiting aircraft carrier USS Carl Vinson for his burial by sea.

"Bin Laden's body was prepared for burial according to Muslim traditions, draped in a white shroud, given final prayers in Arabic, and then placed inside a heavy black bag," Panetta wrote in his latest book 'Worthy Fights: A Memoir of Leadership in War and Peace' which hit the book stores today. "Three hundred pounds of iron chains were put inside as well, to ensure that the body would sink," he wrote.