Russian Foreign Ministry Sergey Lavrov said Tuesday that U.S. investigators have no evidence that Russia meddled in the U.S. election, because if they had any proof, it would have leaked by now.

"The fact that almost a year has passed with so many people involved in the process, and there is still not a single leak about a fact that would confirm these accusations says a lot," Lavrov said in an interview, according to Russia's state-owned news website Tass.

"American society in general, especially in terms of foreign affairs, is built on leaks, and it is impossible to seal up the processes used to investigate the so-called Russian intervention," Lavrov said. "Therefore, they simply do not have these facts."

Democrats continue to insist that Russia played a key role in boosting Donald Trump over Hillary Clinton last November. Clinton on Monday called it a " cyber 9/11."

Last month, it became clear that accounts linked to Russia bought about $100,000 worth of ads on Facebook. But analysts have said that effort likely had a minimal effect on the election outcome.

This year, emails showed that Donald Trump Jr. appeared to agree to meet with a Russian lawyer who promised damaging information on Hillary Clinton. But other emails showed that meeting was about Russia's adoption policy.

Special counsel Robert Mueller has been working for months to investigate the full scope of issues related to charges that Russia tried to influence the 2016 election, including whether Trump's team colluded with Russia. In early October, the Senate Intelligence Committee said it was unable to decide yet whether there is any evidence of collusion.