(Recasts, ands details from source briefed on the review)
WASHINGTON, Oct 9 (Reuters) - Google has discovered Russian operatives spent tens of thousands of dollars on ads on its YouTube, Gmail and Google Search products in an effort to meddle in the 2016 U.S. presidential election, a person briefed on the company's probe told Reuters on Monday.
The ads do not appear to be from the same Kremlin-affiliated entity that bought ads on Facebook Inc, but may indicate a broader Russian online disinformation effort, according to the source, who was not authorized to discuss details of Google's confidential investigation.
The revelation is likely to fuel further scrutiny of the role that Silicon Valley technology giants may have unwittingly played during last year's election. U.S. intelligence agencies have concluded that Moscow's goal was to help elect Donald Trump.
Google has uncovered less than $100,000 in ad spending potentially linked to Russian actors, the source said.
Both Twitter Inc and Facebook recently detected and disclosed that suspected Russian operatives, working for a content farm known as the Internet Research Agency in St. Petersburg, Russia, used their platforms to purchase ads and post content that was politically divisive in a bid to influence Americans before and after the November 2016 presidential election.
The Internet Research Agency employ hundreds of so-called "trolls" who post pro-Kremlin content, much of it fake or discredited, under the guise of phony social media accounts that posed as American or European, according to lawmakers and researchers.
Facebook announced last month it had unearthed $100,000 in spending by the Internet Research Agency and, under pressure from lawmakers, has pledged to be more transparent about how its ads are purchased and targeted.
Google's review had been more robust than ones undertaken so far by Facebook or Twitter, the source said.
Russia's ad purchases were first reported by the Washington Post.
Google, owned by Alphabet Inc, did not deny the story, and in a statement pointed to its existing ad policies that limit political ad targeting and prohibit targeting based on race or religion.
"We are taking a deeper look to investigate attempts to abuse our systems, working with researchers and other companies, and will provide assistance to ongoing inquiries," a Google spokeswoman said on Monday.
Google runs the world's largest online advertising business and YouTube is the world's largest online video site.
Congressional committees have launched multiple investigations into the Russian interference. Both Republican and Democratic lawmakers have said Russia intended to sow discord in the United States, spread propaganda and sway the election.
Google officials have been invited to testify publicly about Russian attempts to use their platforms to influence the election before both the House and Senate intelligence committees on Nov. 1 alongside Facebook and Twitter. While Facebook and Twitter have confirmed plans to attend, Google has not. (Additional reporting by Makini Brice in Washington; Editing by Doina Chiacu and Jeffrey Benkoe)