Joshua is scheduled to compete in Manchester on September 13, with Klitschko attempting to defend his world titles in Hamburg against challenger Kubrat Pulev a week earlier.
Depending on the longevity of Klitschko's career, it is unclear whether the two Olympic gold medallists will ever meet in a competitive bout, but it would have been considered an invaluable experience for Joshua to work alongside the unified title holder in training.
Anthony Joshua is in camp for sparring. Two Super Heavyweight Olympic gold medalists in one ring that's unique. pic.twitter.com/hLWYvLhGDj— Klitschko (@Klitschko) August 19, 2014
Joshua has won his first seven matches as a professional, all inside the opening two rounds.