Standard & Poor's has warned that the European Central Bank (ECB) may have to print more money to maintain recovery in the eurozone.
The ratings giant said that while the currency bloc is climbing out of recession, the recovery will be arduous and unevenly balanced.
Economists also warned that the slowing inflation rate could tip over into deflation in some weaker economies.
The research report gives no assessment of Ireland, but its findings reinforce the fact that while growth has returned to the eurozone, the recovery is tentative.
It said the Frankfurt-based ECB may not be able to wait until the European-wide stress tests are completed at the end of next year before taking further measures to boost the economy, especially because of the fall in inflation.
The inflation rate across the eurozone rose to 0.9% in November from October, but it remains well below the 2% target laid down by the ECB. The ECB has kept interest rates at a record low.
S&P said there were measures that the ECB could contemplate, provided European leaders press ahead with the institutional aspects of banking union, including a scheme similar to the Bank of England's Funding for Lending.