The outlook for the credit rating is negative, Moody's said in a statement. Slovenia is rated one notch higher, at AA-minus, by both Standard & Poor's and Fitch Ratings.

Moody's also said the downward pressure on the rating stems from a deterioration in government funding conditions due to the ongoing euro zone credit crisis.

Fitch Ratings last week said it had put Slovenia on watch for a possible downgrade, and expects to complete that review by the end of January.

Slovenia was the fastest growing euro zone member in 2007 but was badly hit by the 2008-2009 global crisis due to its dependency on exports. The economy shrank by 8 percent in 2009.

After a year of recovery, Slovenia's economy contracted by 0.5 percent in the third quarter of 2011 signaling another recession might be coming.