Russian operatives likely spent tens of thousands of dollars on ads across Google products, including YouTube and Google search, according to reports. Accounts connected with the Russian government spent $4,700 on search and display ads, while another $53,000 was spent on ads with political material that were purchased from Russian territory, from Russian internet addresses, or with Russian currency, The New York Times reported. The Times cited an unnamed person familiar with the ongoing inquiry by the search giant.

The Washington Post earlier reported that the technology behemoth uncovered the Russian-backed disinformation campaign as it considers whether to testify before Congress next month, also citing anonymous sources familiar with the investigation. Social media companies Facebook and Twitter have already agreed to testify, according to AP. The reports said the company discovered the Russian presence by analyzing information shared by Twitter and Facebook, as well its own research and tips from outside researchers. Facebook recently shared about 3,000 Russian-backed ads with Congress.

Meanwhile, Microsoft Corp said it was looking into whether Russians bought U.S. election ads on its Bing search engine or on other Microsoft-owned products and platforms, after rival Google said it had discovered such ads on its products. A spokeswoman for Microsoft said in a statement in response to questions from Reuters that the company did not yet have any other information to share.