The review for ratings downgrade reflects the longer-run risk associated with misuse of the debt-ceiling instrument, Scope said adding that the U.S. government faced elevated risks during recurrent debt-ceiling crises.

"Recurrent debt-ceiling crises have resulted in phases of debt repayment distress for the federal government and dependence on last-minute congressional action to ensure repayment of the United States' debt in full and on time", Scope said in a statement.

Scope also placed United States' S-1+ short-term issuer ratings in local and foreign currency under review for downgrade.

(Reporting by Jose Joseph in Bengaluru; Editing by Sandra Maler)