Standard & Poor's on Thursday revised down its sovereign credit outlook for the United Kingdom's AAA rating to negative from stable citing the potential for delayed and uneven economic recovery.

S&P said the revision was driven by an expectation that net general government debt as a percentage of gross domestic product will continue to rise in 2015 before declining again.

"We are therefore revising our outlook on the unsolicited long-term ratings on the U.K. to negative, from stable, reflecting our view of a one-in-three chance that we could lower the ratings if the U.K.'s economic and fiscal performances weaken beyond our current expectations," S&P said in a statement.