KIEV, April 25 - Raiffeisen International Bank AG, the biggest foreign lender in the former Soviet Union, was close to selling its smaller Ukrainian unit to OTP Bank of Hungary for $500 million, a Ukrainian official said.

Raiffeisen has been in talks since early April trying to sell its JSCB Raiffeisenbank Ukraine, the smaller of its two Ukrainian units, after deciding that the merger costs would be too high.