November 17 (SeeNews) - Fitch Ratings said it has upgraded the viability rating (VR) of Croatia's top lender Zagrebacka Banka (ZABA) [ZSE:ZABA], part of Italy's UniCredit Group, to 'bbb-' from 'bb+' and has affirmed its long-term foreign-currency issuer default rating (IDR) at 'BBB' with a stable outlook.