Moody's Investor Service downgraded the credit ratings of Spain, Italy, Portugal, Slovakia, Slovenia, and Malta on Monday.
Moody's said the governments of these countries haven't done enough to take care of their debt problems.
While the rating's agency allowed France, Britain, and Austria to retain their top rating, they lowered their outlook on those nations to "negative" from "stable."
"All of these ratings remain on negative outlook given the continued uncertainty regarding financing conditions over the next few quarters and its corresponding impact on creditworthiness," Moody's said in a statement.
The negative outlook means that during the next 18 months there's a 40 percent chance the agency could cut the AAA ratings of those nations as well.