Oil prices slumped to just above 46 dollars here on Tuesday, reaching the lowest point in almost four years, as global energy demand weakened amid a widespread economic slowdown. On London's Intercontinental Exchange (ICE), Brent North Sea crude for delivery in January hit 46.02 dollars -- the lowest point since February 18, 2005. The contract later recovered slightly to stand at 47.43 dollars a barrel, down 53 cents compared to the close on Monday, when Brent had lost a huge 5.52 dollars. Later Tuesday, light sweet crude was down 75 cents at 48.53 dollars a barrel.