Moody's downgraded Russia's credit rating for the second time in a week amid the war in Ukraine.

Russia's long-term issuer and senior unsecured local- and foreign-currency debt ratings were lowered to Ca from B3, the rating agency said late Sunday. The outlook is negative.

Capital controls by the Russian central bank will restrict cross-border payments including for debt service on government bonds, it said in a statement.

The rating downgrade is driven by concerns around Russia's willingness and ability to pay its debt obligations, it added.

"The negative outlook reflects the significant risks to macroeconomic stability posed by the imposition of severe and coordinated sanctions following Russia's invasion of Ukraine," the statement said.

Moody's first lowered Russia's credit rating to B3 from Baa3 on March 3./aa