The discovery by Google is also significant because the ads do not appear to be from the same Kremlin-affiliated troll farm that bought ads on Facebook - a sign that the Russian effort to spread disinformation online may be a much broader problem than Silicon Valley companies have unearthed so far.
Russian Federation used Google to intervene in the United States presidential election in 2016, said the influential American newspaper the Washington Post, citing sources familiar with the results of an internal investigation.
The Washington Post reports that Google found the Russian links to ads on its platforms by using data from Twitter accounts. Google discovered potential Russian ads by linking Russian Twitter accounts to those used to purchase ads on its own services, reportedly without Twitter's permission.
Although Google has made no official statement since its earlier denial, The Washington Post reports company sources describing new evidence. The company is looking at a set of ads that cost less than $100,000 in total, according to the report.
Facebook said the Russian ads reached at least 10 million of its 210 million American users.
Congressional committees have launched several investigations into the Russian interference in the US presidential elections.
Google has declined to provide a comment on the story to the newspaper.
A Google spokeswoman, Andrea Faville, said the company had a policy that limits political ad targeting and prohibits targeting based on race and religion.
But after launching a review, the company found around $100,000 (£76,000) in ad spending potentially linked to Russian sources, according to a source.
Global social media platform Facebook, meanwhile, has also recently said that it had to shut down thousands of fake accounts in the run up to the German election last month.
Though the videos were only viewed hundreds of times, they demonstrated for the first time that Russian Federation allegedly deployed real people, not just fake online accounts or bots, to further spread propaganda. Critics are angry that Facebook won't reveal the Russian ads to the public, and many diverse voices are calling for tighter government regulations over the company. As a result, Twitter identified about 200 related, Russia-tied accounts on its platform, though none of them had been registered as advertisers.
Google will join Facebook and Twitter in giving evidence before congress in November.