The chief executive of German power utility E.ON on Tuesday rejected calls for the industry to halt imports of so-called "dirty power" from eastern Europe."I understand the thinking behind the idea, but believe it will be absolutely impossible to agree to a voluntary self restraint on power imports, as demanded by economics minister Werner Mueller," Ulrich Hartmann told the Sueddeutsche Zeitung. Dirty power is defined as electricity from plants fired by high emissions-producing fossil fuels or nuclear energy.