Acting Director, Banking Supervision Department of the CBN, Adetona Adedeji, gave the warning in a statement on Monday, in Abuja.
Adedeji said that the current practice of using foreign currency-denominated collaterals for Naira loans would only be allowed in the case of Eurobonds issued by the Federal Government.
He said that guarantees of foreign banks, including standby letters of credit would also be allowed