The rating agency Moody's has lowered its outlook for raised a question over fiscally strong countries Germany, the Netherlands and Luxembourg.
Moody's said the move was due to the mounting uncertainty that they would have to provide further aid to Spain and possibly Italy.
Germany, the Netherlands and Luxembourg all have the highest possible rating - triple A - however Moody's says their outlook is now 'negative' - suggesting they could be downgraded in the near future.
In its latest analysis, Moody's said said that the increasing likelihood that Greece could withdraw from the single currency deepens the crisis.
The German government has downplayed the Moody's decision to place Europe's biggest economy on a negative outlook.
The Finance Ministry noted in a statement late Monday that Moody's Investors Service had kept Germany's Aaa credit rating, the highest possible.
The government said the risks cited by Moody's weren't new and were largely based on a short-term assessment.
It said Germany "remains in a very solid economic and financial situation."
