“We have done nothing more than to buy time until we have brought order to (eurozone countries’) competitive differences and to the budget deficits of individual euro countries,” she said on Sunday.

Asked his view of Merkel’s comments, following a plunge on Friday for stock markets and the euro, which deepened until it hit a four-year low on Monday, Juncker did not hold back.

“In my opinion, certain people would do better to think before they speak,” Juncker told reporters as he arrived in Brussels to chair a monthly meeting of finance ministers from the 16 countries that share the euro currency.

He said that, for the benefit of the markets, and of Europe’s ordinary citizens, “sometimes they would do better to keep their mouths shut.”

Of reports that Germany wants its euro partners to place a legal limit on annual deficits, similar to a new constitutional ceiling there of 0.35 percent of national output from next year, Juncker said the ministers would “have to see how far such a measure could command general support.”

He said it was “obvious” that eurozone countries have to do everything possible to cut deficits and debts, but said that these efforts should not come at the expense of action to favour economic growth in the short-term.

Juncker said that “personally,” he thought the Spanish government had taken “courageous” decisions that did not lack “ambition,” but that he would wait until a report by the European Union’s budgetary watchdog, the European Commission, before judging whether the austerity plans “can be considered as having been sufficient.”