The ratings agency Fitch on Friday downgraded the credit ratings of five eurozone countries, including Italy and Spain, DPa reported.
Italy was downgraded from A+ to A- and Spain from A to AA-, citing financing and monetary problems facing members of the single currency bloc.
Belgium, Slovenia and Cyprus were also downgraded.
The announcement came ahead of a European Union summit on Monday to discuss ways to put the continent back on a growth trajectory.
Earlier this month, ratings agency Standard & Poor's (S&P) downgraded the debt rating of nine European countries, including France and Austria, who were stripped of their prized top-notch triple A ratings.
Italy, Spain, Portugal and Cyprus were lowered two levels, while Malta, Slovakia, and Slovenia each fell one level.
Germany, the Netherlands, Finland and Luxembourg hung on to their top AAA ratings. Belgium, Estonia and Ireland also maintained their lower-level credit scores.
Over the past two years, EU officials have often criticized the wisdom of ratings agencies, arguing that rather than warning investors about future risks, they have exacerbated market tensions by exaggerating the extent of the eurozone's financial problems.
The same officials repeatedly pointed out that S&P and the two other firms that dominate the ratings market - Fitch and Moody's - failed to spot problems in US investment bank Lehman Brothers, whose collapse in 2008 sparked a global financial crisis.
At the World Economic Forum in Davos, Switzerland on Friday, US Treasury Secretary Timothy Geithner said efforts to help stem the eurozone crisis would depend on the steps that Europe took first.
"Our view is that the only way Europe is going to be successful in holding this together, making monetary union work, is to build a stronger firewall," he said.