The head of Germany's central bank on Saturday voiced his "scepticism" about the ECB's decision to launch a trillion-euro bond-buying programme in a bid to ward off deflation and boost the eurozone economy.
"I regard this decision with scepticism," the Bundesbank president Jens Weidmann told the German daily Bild.
Weidmann is a member of the the European Central Bank's council of governors that approved of the stimulus plan known as quantitative easing (QE) but he did not agree with the decision announced on Thursday.
"Buying sovereign debt, in a single currency union, is not like any other (monetary) tool. It brings risks," Weidmann told the paper.
Critics, particularly in Germany, Europe's biggest economy, complain that the QE is a licence to print money to get governments out of debt and will lessen pressure for reform.
The ECB plan to buy 60 billion euros ($69 billion) of public and private sector bonds per month from March through September 2016 will mean that the central banks of eurozone countries will be "among the states' biggest creditors", Weidmann said.
He stressed the need for debt-hit countries not to be "negligent" with their budgets and to continue on a path of reforms to turn around their economies, a view also expressed by German Chancellor Angela Merkel on Friday.
Opponents of QE are also concerned that taxpayers in stronger economies such as Germany's will have to foot the bill should any country default on its debt.
But the ECB says its plan has been designed so that only 20 percent of the risk will be shared among the 19 nations using the euro. The rest will be shouldered by the national central banks of the countries concerned.