Saudi Arabia's ailing Crown Prince Sultan bin Abdul Aziz is reportedly in a state of coma after undergoing surgery in a New York hospital. “The Saudi crown prince went into a coma hours after he was operated on for an unidentified cancer on Wednesday. He is still unconscious and has shown no sign of improvement or indication that he is likely to recover,” said an informed source that declined to be identified, quoted by IRNA on Monday. The source reportedly did not further elaborate on Prince Sultan's condition and refused to be identified. Prince Sultan, who is believed to be in his eighties and has served as defense minister for the past 50 years, has been battling cancer for several years and reportedly spent all of 2009 in American hospitals. The development comes as Saudi Arabia's King Abdullah was also taken to the United States to undergo medical treatment on a herniated disc in his back in November 2010. The 86-year-old monarch first underwent a successful operation on November 24. He had a follow-up back surgery on December 3 to stabilize several vertebrae in his spinal column. Prince Nayef, second in line of succession to the Saudi throne, is reported to be in a failing health state as well. He has been receiving medical treatment for an unspecified illness in the past 20 months. Prince Nayef, 78, has been Saudi Arabia's interior minister for the past 35 years. The royal succession is a highly sensitive subject of debate in Saudi Arabia. Many analysts expect a major power struggle for the Saudi throne as all potential candidates are elderly and ailing.