ROME, Sept 22 (Reuters) - An “error of procedure” at the Vatican bank is being exploited to attack the Vatican with a money-laundering investigation, the bank’s president said in an interview published on Wednesday.

Vatican bank officials are under investigation for suspected money laundering and police have frozen 23 million euros ($30.21 million) of its funds, Italian judicial sources said on Tuesday.

The bank’s president Ettore Gotti Tedeschi told financial daily Il Sole 24 Ore he felt humiliated by the investigation and that it was all centered around a mistake.

“An error of procedure is being used as an excuse to attack the institute, its president and the Vatican in general,” Gotti Tedeschi told the paper.

He said the operation in question “was a normal treasury operation and it involved a transfer from accounts of the Vatican bank to other accounts of the Vatican bank.”

He added that in the past 10 months the bank “has been adapting all its internal procedures to be in harmony with international transparency standards.”

Gotti Tedeschi and the bank’s director-general Paolo Cipriani have been put under investigation by Rome magistrates Nello Rossi and Stefano Fava in a case involving alleged violations of European Union money laundering regulations.

The Vatican expressed “perplexity and amazement” at the actions by the Rome magistrates and “utmost faith” in the two men who head the bank, officially known as the Institute for Religious Works (IOR).

The judicial sources said Italy’s financial police had preventively frozen 23 million euros of the IOR’s funds in an account in an Italian bank in Rome.

Two recent transfers from an IOR account in the Italian bank were deemed suspicious by financial police and blocked. One was a transfer of 20 million euros to a German branch of a U.S. bank and another of 3 million euros to an Italian bank.

The IOR principally manages funds for the Vatican and religious institutions around the world, such as charity organisations and religious orders of priests and nuns. (Reporting by Catherine Hornby; Editing by Peter Graff)