The world's financial markets should take some of the blame for creating the precarious situation in Greece and the other troubled nations in the euro zone, Deutsche Bank CEO Josef Ackermann told CNBC Friday.
"We've created this kind of imbalance," he said. "I have to be self-critical. The financial markets have not put enough discipline on Greece and other countries."
"How is it possible to raise almost 300 billion euros or more at very attractive rates, although we knew that Greece was, from an economic point of view, a much weaker country than Germany or France?" he asked.
The task now is to reduce Greece's fiscal deficit and create a sustainable economy. However, he said, "You can't do that overnight. We've built up this imbalance today over many, many years and it will take longer to bring that down to a sustainable level."
He hopes the International Monetary Fund and the European Union will decide soon on whether they will give Greece more funds.
"We have to have clarity in the coming days," Ackermann said. "I do hope it happens. If they delay until September, who knows what will happen over the summer break in terms of discussion?"
On Friday, Chancellor Angela Merkel announced German support for a new aid package for Greece that would include voluntary private sector participation.
As Greece's government faces the task of asking the population to accept yet more austerity measures, Ackermann said it was necessary to include the private sector: "We are studying whether we can voluntarily contribute somehow, in order to get the political support. But on the other hand, I think there's no other option than to inject the necessary funds."
Ackermann said Deutsche Bank's exposure to Greece is very small, so he's "not overly concerned" if Greece defaults.
However, he added, "What I cannot say is what it means to financial markets in general, and whether we would have similar dislocations as we had when Lehman collapsed. That's an unknown. Then, of course, things can get worse."