Rating agency Fitch Ratings on Thursday affirmed Japan's sovereign debt rating at 'A'. The outlook is 'stable'.

"The key factor constraining the rating is high and rising government debt," Fitch said.

The agency expects Japan's gross general government debt to reach 245% of GDP by end-2016.

Japan's general government budget deficit is forecasted to be 4.8% of GDP in 2016.

"The Stable Outlooks reflect Fitch's assessment that upside and downside risks to the ratings are currently broadly balanced," the agency said.