Marcus Chromik, Commerzbank's chief risk officer, told a parliamentary committee that the bank agreed to extend credit in 2018 to Wirecard based on assurances about the company's prospects by top executives, as well as the testimonials of auditors.
Commerzbank internally carried out its own careful analyses, he said.
"There were no signs of accounting discrepancies," said Chromik, one of several senior bankers to field questions at the investigative committee into Wirecard on Thursday.
"Commerzbank, like many others, was a victim of an unimaginable fraud of a huge dimension," he said.
Lawmakers have been investigating the implosion of the German tech star once worth $28 billion, which folded owing billions.
Wirecard last year filed for insolvency in what politicians, regulators, prosecutors and former executives say was a sophisticated global accounting fraud.
Wirecard's demise has embarrassed Germany, which prides itself on a reputation for rectitude and reliability, amid criticism that authorities ignored red flags.
Commerzbank began asking more questions of Wirecard as press reports shed doubt on Wirecard's operations, Chromik said. The bank ended its relationship with the company in May 2019 as it grew concerned about the risk of possible money laundering, he said.
(Reporting by Christian Kraemer and Patricia Uhlig; writing by Tom Sims;Editing by Elaine Hardcastle)