Justin Bieber has been urged to cancel his forthcoming concert in Saudi Arabia next month by the fiancée of murdered Washington Post journalist Jamal Khashoggi.The pop star is due to perform in the city of Jeddah on December 5 as part of the Formula One Saudi Arabian Grand Prix.But Hatice Cengiz has called on Bieber to cancel the show.In an open letter published in the Washington Post, Ms Cengiz wrote: “Do not sing for the murderers of my beloved Jamal.