Supermarket group Tesco, Britain's biggest retailer, on Wednesday announced a massive jump in annual net profits, but its underlying performance showed a fall. Tesco said profit after tax stood at £974 million ($1.63 billion, 1.18 billion euros) in 2013 compared with £28 million for 2012. But pre-tax profits dropped almost 7.0 percent to £3.05 billion, the company said in a statement.