An apparatus for continuous casting of metals has members (16) adapted to generate a stationary magnetic field of a variable strength over substantially the entire horizontal cross section of the mould from one long side to the other long side close to, or below, the region for supply of molten metal at a distance below the upper surface of the molten metal. There are also members (17) adapted to generate a variable magnetic field in the area of the upper surface in a region that is centrally located with respect to said cross section and close to a region for supply of molten metal. A unit (12) is adapted to control said magnetic members (16, 17) to generate, independently of each other, magnetic fields with an appearance that is dependent on the value prevailing of one or more predetermined casting parameters.