The COVID-19 pandemic made the need for change all the more pressing, Regling, who runs the euro zone's powerful European Stability Mechanism, told a seminar of the Belgian central bank.
"In my view the 3% deficit limit remains relevant, and that's good because it's also mentioned in the Treaty. But we need to think about the debt limit. Or I should say a debt target of 60%, which made sense when the Maastricht Treaty was negotiated, but it doesn't make sense now," he said.
The calculations are likely to fuel a debate in Germany about when Berlin should end massive deficit-spending triggered by the COVID-19 pandemic, and return to the fiscal rules of a debt brake that parliament suspended for 2020 and 2021.
Deputy Finance Minister Bettina Hagedorn said the calculations were only estimates and fraught with uncertainty due to the long time period.