The former mayor of New Orleans has revealed how he became so paranoid after Hurricane Katrina he was convinced the government was trying to poison him.

Ray Nagin also tells the bizarre story of how heavily-armed men in combat suits allegedly stormed his command centre and attempted to plant bugs, as he led the response to the 2005 disaster.

He makes the revelations in a self-published memoir, Katrina's Secrets: Storms After the Storm.