Leading credit rating agency Fitch Ratings lowered its outlook on China's sovereign credit rating to "negative" from "stable" on Tuesday.

The firm says China's fiscal policy will become increasingly important to support economic growth over the next several years, and that government debt is expected to rise.

Fitch kept China's sovereign credit rating unchanged at "A+," the fifth-highest level.

China's Finance Ministry on Wednesday called the outlook downgrade regrettable. It said the long-term positive momentum of the Chinese economy has not changed, and the government's ability and determination to maintain sound sovereign credit also remain unchanged.

Moody's also cut its outlook on China's sovereign credit rating from "stable" to "negative" in December of last year.