Deutsche Bank Chief Executive Josef Ackermann on Thursday warned that haircuts on sovereign debt combined with demands to boost bank capital could lead to a credit crunch in the real economy. Ackermann's comments are in response to comments yesterday from four euro zone officials who told Reuters that a "haircut" of between 30 and 50 percent for Greece's private creditors was under consideration. "A question remains over whether banks will be able to provide financing, or whether possible haircuts in the euro zone and the new regulatory environment will practically force them to be restrictive," Ackermann told a conference of corporate executives gathered in Berlin . Before considering further measures to stabilize the euro zone politicians and regulators should consider the cumulative impact of proposals such as forced recapitalization, a transaction tax and writedowns on bonds. Given the robust performance of the German economy so far, Deutsche Bank currently sees no need to tighten lending requirements for German companies, he said. The German government expects gross domestic product growth of 3% this year, which would provide vital economic stimulus to a euro zone that has become increasingly dependent on Germany as the debt crisis intensifies. Germany's most high profile banker said it is doubtful whether a blanket recapitalization of European banks - a measure being considered by politicians in Germany and France - would help solve the sovereign debt crisis. [CNBC 10/13/11]