Japan's sovereign credit rating was cut for the first time in nine years on concern that Prime Minister Naoto Kan hasn't done enough to curb the $11 trillion debt burden.

The nation's debt is now ranked by Standard & Poor's as AA-, the fourth-highest level and the same as China's. The reduction from AA was announced Thursday.

The move fuels concern that policymakers may struggle to finance a debt burden projected to swell to ¥943 trillion, or about twice the size of the nation's gross domestic product. Kan may need to speed up efforts to raise revenue by raising the consumption tax to prevent a debt crisis like that of Europe.