Donald Trump sought on Monday to discredit a New York Times report that Deutsche Bank employees flagged concerns over transactions involving legal entities controlled by the president and his son-in-law, Jared Kushner.
The Times said the nature of the transactions was not clear and that the bank ultimately took no action. Some of the transactions involved money flowing back and forth with overseas entities or individuals, some in Russia.
Trump claimed he did not "need or want banks" and does not receive money from Russia.
Congress and New York state are investigating the relationship between Trump, his family and Deutsche Bank, and demanding documents related to any suspicious activity.
Trump has sued in court in an attempt to block House subpoenas for his financial records that were sent to Deutsche Bank, Capital One and the accounting firm Mazars.
The Times report said anti-money-laundering specialists at Deutsche Bank recommended in 2016 and 2017 that multiple transactions be reported to a federal financial-crimes watchdog.
Citing five current and former Deutsche Bank employees, the report said executives at the German-based bank, which has lent billions to Trump and Kushner companies, rejected the advice and the reports were never filed.
Earlier this month, the Times obtained tax information which showed his businesses lost more than $1bn from 1985 to 1994. Trump has refused to release more recent tax returns or to comply with House subpoenas for them.
Trump rejected and ridiculed that story. In his Monday tweets, he claimed not to need banks as he "made a lot of money and buys everything for cash".
He also said the "fake media … always uses unnamed sources (because their sources don't even exist)".
But one former Deutsche Bank employee, Tammy McFadden, who reviewed some of the transactions, spoke to the Times on the record. She said she was fired last year after raising concerns about the bank's practices, the Times said.
McFadden said concerns she raised included contacts between Kushner Companies and Russian individuals in summer 2016. Deutsche Bank has been fined for laundering billions of dollars for Russians.
In his report on Russian election interference released in redacted form last month, special counsel Robert Mueller did not find that Trump conspired with Moscow. But he did lay out extensive contacts between Trump aides and Russia.
On Monday, Trump tweeted: "The new big story is that Trump made a lot of money and buys everything for cash, he doesn't need banks. But where did he get all of that cash? Could it be Russia? No, I built a great business and don't need banks, but if I did they would be there."
Trump also called the Times reporting "phony" and called Deutsche Bank "very good and highly professional".
Deutsche Bank denied the report but it contributed to shares falling to a record low. Shares in the German lender were down by 2.8% at the time of writing. The bank was recently forced to abandon merger plans with Commerzbank. It has also struggled to turn around its corporate and investment arms.
The Times said the transactions in question, some of which involved Trump's now-defunct foundation, set off alerts in a computer system designed to detect illicit activity, according to the former bank employees.
Compliance staff members who reviewed the transactions prepared suspicious activity reports they believed should be sent to a unit of the US treasury that polices financial crimes, according to the newspaper.
A spokeswoman for the Trump Organization told Reuters "the story is absolute nonsense".
"We have no knowledge of any 'flagged' transactions with Deutsche Bank. In fact, we have no operating accounts with Deutsche Bank," she said.
The newspaper said a Kushner Companies spokeswoman called any allegations of relationships involving money laundering "made up and totally false".