"There is good reason to hope that the crisis is over in two to three years' time," European Financial Stability Facility (EFSF) chief Klaus Regling said, according to a preview of the weekly German magazine.
But this depended on member states continuing to implement reforms aimed at sorting out their budgets, he said.
Regling dismissed the idea that the euro zone could break apart. Both weaker and stronger countries had a collective interest in seeing it survive, he said.
"The risk that the euro is discarded, from whatever quarter, is zero," he said, criticizing occasional "hysteria" in Germany on this topic.
He said his fellow countrymen expected everything to get worse, but that this was the wrong attitude.
"The signs point to an improvement," he said, adding that the economic fundamentals in euro zone countries appeared to be improving.
(Reporting by Sylvia Westall; Editing by David Holmes)