The Kremlin says a U.S. Treasury official's comments to the BBC on Putin being corrupt "amount to an official accusation."
"It's an official accusation," Putin's spokesman Dmitry Peskov told journalists in a conference call.
"[Bilateral] relations are now in such a state that a lie like this is unlikely to aggravate them even further," he added.
Adam Szubin, acting Treasury secretary for terrorism and financial crimes, said in an interview with BBC Panorama that the Russian president had been amassing secret wealth.
The BBC report said Szubin declined to comment on a 2007 Central Intelligence Agency report that estimated Putin's wealth at $40 billion, but he said the Russian leader's stated wealth was an underestimation.
The Kremlin has denied such allegations.
For his part, Putin has repeatedly said that he has read press reports about his immense wealth, including that he was even the world's richest man, but he has denied those reports as nonsense.
The United States has placed sanctions on a number of Russian businessmen loyal to Putin as part of its drive to put pressure on Russia for its intervention in Ukraine.