Olli Rehn believes a digital euro "in one form or another" is all but inevitable.
How the firm helping lead Estonia's central bank digital currency research is approaching a mass-market crypto coin.
The "priority" research comes as Spain weighs a global pivot to digital economies.
The EU's central bank has laid a claim to the phrase "digital euro" before deciding whether to actually issue one.
A digital euro for retail payments would "ensure that sovereign money remains at the core of European payment systems," according to Lagarde.