Supercharged internal combustion engine and method for improving the emission behaviour of an internal combustion engine

The engine has an intake line supplying fresh air, and an exhaust-gas line discharging exhaust gas. Each of two exhaust-gas turbochargers (6, 7) has a turbine and a compressor arranged in the exhaust-gas and intake lines, respectively. An exhaust-gas after treatment system (8a) arranged downstream of one of the turbine, and another exhaust-gas after treatment system (8b) arranged between the two turbines. An independent claim is also included for a method for operating a pressure-charged internal combustion engine.