Fitch Ratings withdrew all of Suncorp Group's (ASX:SUN) ratings, citing commercial reasons, according to a Thursday release.

Before the withdrawal, the rating agency downgraded the Australian-based financial group's long-term issuer default rating to A from A+ and subordinated debt rating to BBB+ from A-

Fitch also affirmed the company's F1 short-term issuer default rating and removed all of them from Rating Watch Negative.

The downgrade reflects Suncorp's weaker Fitch prism global score after the sale completion of its fully owned bank in July.

The bank sale led to the group's prism score falling to "adequate" due to a smaller capital base, Fitch said.