Oil prices sank under 54 dollars a barrel here on Wednesday, hitting the lowest level since January 2007, as traders worried about the gloomy economic outlook and weaker energy demand, analysts said. In afternoon London trade, Brent North Sea crude for delivery in December plunged as low as 53.37 dollars per barrel, which was last seen on January 30, 2007. New York's main contract, light sweet crude for December delivery, fell as low as 57.04 dollars a barrel, which was last witnessed in March 2007.