Tax cuts announced by Britain's government this week will not held rebuild its diminished fiscal headroom, rating agency S&P Global said on Friday, although its finances will get a boost if the UK economy does better than expected next year.

"Stabilizing or reducing public debt levels will remain a key challenge," S&P added, which currently has a AA rating for the UK and a "stable" outlook, which signals it is not expected to move in either direction in the near term. (Reporting by Marc Jones; Editing by Amanda Cooper)