SAN FRANCISCO • Google has discovered that Russian operatives spent tens of thousands of dollars on ads on YouTube, Gmail, Google search and other products in an attempt to interfere in the US presidential election last year, according to people familiar with the company's investigation.

The discovery by Google is 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.

Google previously downplayed the problem of Russian meddling on its platforms. Nevertheless, it launched an inquiry, as Congress pressed technology companies to determine how Russian operatives used social media, online advertising and other digital tools to influence the election and foment discord in US society.

"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 spokesman said yesterday.

The people familiar with its investigation said the company is looking at a set of ads that cost less than US$100,000 (S$136,000) and that it is still sorting out whether all of the ads came from trolls or whether some originated from legitimate Russian accounts.

Google has so far mostly avoided the scrutiny that has fallen on its rival, Facebook. The social network recently shared with congressional investigators about 3,000 ads that were bought by operatives linked to the Internet Research Agency, a Russian-government affiliated troll farm, the company has said.

Meanwhile, Twitter said it has shut down 201 accounts associated with the Internet Research Agency. It also said the account for the news site RT, which the company linked to the Kremlin, spent US$274,100 on its platform last year.

Google discovered the Russian presence on its platforms by siphoning data from another technology company, Twitter, the people familiar with the investigation said.

Twitter offers outsiders the ability to access a small amount of historical tweets for free, and charges developers for access to its entire firehose of data going back to 2006.

Google downloaded the data from Twitter and was able to link Russian Twitter accounts to other accounts that had used Google's services to buy ads, the people said. This was done without the explicit cooperation of Twitter.

Google is also sharing data with Facebook. Executives for Facebook and Twitter will testify before congressional investigators on Nov 1.

Google has not said whether it will accept a similar invitation to do so.

WASHINGTON POST