Washington, July 27: Film director Steven Spielberg may quit his position as artistic advisor to the 2008 Beijing Olympics if China does not take a harder line against Sudan over Darfur, ABC News reported. China, a huge investor in Sudan's oil industry, has resisted sending U.N. peacekeepers to the country's troubled Darfur region. Human rights groups and other critics have accused China and others of breaching international rules and fanning bloodshed by selling Sudan weapons that have been diverted to Darfur......