President Vladimir Putin felt insulted by allegations of Russian interference in the US election, Donald Trump said after meeting him briefly at an Asia-Pacific summit in Vietnam.
"You can only ask so many times... he said he absolutely did not meddle in our election," President Trump said.
President Putin later described the allegations of meddling as "absurd".
The justice department is investigating the claims, as well as alleged collusion involving Mr Trump's team.
Several key former aides have already been named in connection with the inquiry.