A member of the European Central Bank's executive board, Sabine Lautenschlaeger, has expressed doubt that its bond purchase programme will have the desired effect.
The ECB launched a programme of so-called quantitative easing at the beginning of March in order to drive inflation higher in the 19 countries that share the euro and help kick-start economic recovery.
Under the programme, the ECB aims to buy €1.14 trillion worth of bonds between now and September 2016 at a rate of €60bn per month.
"Given the current low level of interest rates in the euro zone, I have doubts whether the economic effects of the purchase programme will reach the desired magnitude," Lautenschlaeger told the weekly magazine WirtschaftsWoche.
"Experience in the United States shows that sovereign bond purchases are more effective the higher yields are," Lautenschlaeger said.
She warned that low interest rates could lead to the formation of asset price bubbles.
"When interest rates are low, the danger increases of risky investment behaviour, and that can easily lead to overheating or to price bubbles in other asset classes," she argued.
In addition, low interests took the pressure off governments to push through economic reforms and get their finances in order.
Before joining the ECB's executive board, which is responsible for the day-to-day running of the bank, Lautenschlaeger was vice president of the German central bank or Bundesbank.
And her scepticism towards the QE programme is shared by Bundesbank chief Jens Weidmann.
As of March 27, the ECB had acquired €41.02bn of sovereign bonds under the programme, according to data published on the ECB website.