KPMG said on Thursday that the firm acted professionally and ethically in all its dealings with Pilatus Bank, "in line with the professional standards it adhered to and applied for all its clients".
KPMG acted as consultants to Pilatus Bank during the licensing process.
Last December, the international audit firm faced questions from MEPs investigating the rule of law in Malta.
Asked if the chairman's Iranian origins and use of a St Kitts & Nevis passport were obstacles during the licensing process, Juanita Bencini, former partner at KPMG, had told MEPs she could not answer due to client confidentiality obligations.
In its statement on Thursday, the firm reiterated that Maltese law concerning client confidentiality prevented it from commenting further.
Pilatus Bank was set up by Iranian national Ali Sadr. He is facing up to 125 years in jail after being arrested in the United States over charges of money-laundering and sanction busting.
Mr Sadr is accused of evading US sanctions against Iran by filtering $115 million through front companies and foreign bank accounts, to mask Iranian business dealings in Venezuela between April 2011 and November 2013.
Just last year, the controversial bank was at the centre of the Egrant scandal that stirred a political storm in Malta.
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