Ratings agency Standard & Poor's (S&P) downgraded Japan's credit rating to A+ from AA- to A+ on Wednesday. The outlook was upgraded to stable from negative.

It was the first downgrade by S&P since January 2011.

"Despite showing initial promise, we believe that the government's economic revival strategy - dubbed 'Abenomics'- will not be able to reverse this deterioration in the next two to three years. Economic support for Japan's sovereign creditworthiness has continued to weaken," the agency said.