Fitch Ratings said it has upgraded the Viability Ratings (VRs) of Bulgarian lenders Unicredit Bulbank to 'bb+' from 'bb' and of United Bulgarian Bank (UBB) to 'bb' from 'bb-."Fitch Ratings has affirmed Long-Term Issuer Default Ratings of UniCredit Bulbank AD at 'BBB-', United Bulgarian Bank AD at 'A-' and First Investment Bank AD at 'B'. The Outlooks are Stable," the ratings agency said in a statement late on Friday. First Investment Bank's VR has been affirmed at 'b'. The upgrade of Unicredit Bulbank's VR reflects its improved asset quality. The upgrade of UBB's VR reflects the strengthening of its credit risk profile as a result of significant restructuring following its acquisition by KBC Bank.The affirmation of Bulbank's and UBB's IDRs reflects Fitch's opinion that there is a high and extremely high probability that they would be supported, if required, by their respective parents. Fitch also said in the statement:"KEY RATING DRIVERSIDRS, SUPPORT RATINGS, SUPPORT RATING FLOORBulbank and UBB are based in Central and Eastern European (CEE) region, which is strategically important for UniCredit and KBC.