For months, President Trump and his aides have insisted that they had no contact with Russian officials during the presidential campaign, a denial Mr. Trump repeated last week.
The denial stands at odds with statements by Russian officials, who have at least twice acknowledged contacts with aides to Mr. Trump before the election.
It is not uncommon for a presidential campaign to speak to foreign officials, which makes the dispute particularly unusual. At the same time, any contacts would have taken place during a period when American intelligence agencies believe the Russian government was trying to disrupt the election with a campaign of computer hacking.
The dispute began two days after the Nov. 8 election, when Sergei A. Ryabkov, the Russian deputy foreign minister, said his government had maintained contacts with members of Mr. Trump’s “immediate entourage” during the campaign.
“I cannot say that all, but a number of them maintained contacts with Russian representatives,” Mr. Ryabkov said during an interview with the Interfax news agency.
More recently, Russia’s ambassador to Washington, Sergey I. Kislyak, told The Washington Post that he had communicated frequently during the campaign with Michael T. Flynn, a close campaign adviser to Mr. Trump who became the president’s national security adviser before resigning from the position last week.
“It’s something all diplomats do,” The Post quoted Mr. Kislyak as saying, though he refused to say what subjects they discussed.
Mr. Trump and his aides denied any contacts occurred during the campaign.
“This is a nonstory because to the best of our knowledge, no contacts took place, so it’s hard to make a comment on something that never happened,” Sarah Huckabee Sanders, a White House spokeswoman, said on Monday.
The Russian government did not respond to a message over the weekend seeking comment.
Separately, The New York Times and other news outlets reported last week that Trump campaign advisers and other associates of Mr. Trump’s had repeated contacts last year with Russian intelligence officials. Those reports, citing anonymous current and former American government officials, were vigorously denied by the White House.
On Thursday, Mr. Trump made clear his annoyance when questioned about contacts with Russia.
“How many times do I have to answer this question? Russia is a ruse. I have nothing to do with Russia,” he said during a White House news conference.