Deutsche Bank has brushed off speculation that it has been in merger talks with US giant Citigroup as it reported a fourfold increase in investment banking income.

Josef Ackermann, chief executive of Deutsche Bank, said at a press conference: "We do not comment on market speculation. In any case three things are important and I have always said that : Is it good for shareholders ? Is it good for staff ? Is it good for Germany ? And we will stick to this and would never do anything hurting one of these criteria ?"