Microsoft is reviewing its sales records as part of an investigation into whether Russian-backed groups bought ads on its Bing search engine and other platforms during the 2016 USA presidential election.
Google's internal investigation found $4,700 of search ads and display ads the company believes are Russian-connected, and found $53,000 of ads with political content were purchased from Russian internet providers, building addresses or with Russian currency, people familiar with the investigation said.
Last week, Facebook admitted some 3,400 ads purchased by operatives associated with the Internet Research Agency, a Russian-government affiliated troll farm, had been viewed by 10 million users in the run up to the election.
According to media reports, the US Senate Intelligence Committee has asked senior managers from Facebook, Google and Twitter to testify in front of the US Congress at a public hearing as part of the probe into Russia's alleged attempts to use social media to influence the election. Facebook said they are still conducting the enquiry and are looking at thousands of more ads that seems to bear the same overtures of a possible Russian Federation link.
Congressional committees have launched multiple investigations into Russian interference, but concern about Silicon Valley's role has surged over the past month against the backdrop of a cascade of revelations about how Russia appears to have leveraged their platforms to spread propaganda.More news: India Defense minister teaches Chinese soldiers meaning of 'Namaste'
As the only company that sells more digital advertising than Facebook, Google was also being closely watched in the context of the investigation.
Google is the latest tech company that's found evidence of Russian-bought ads on its platforms.
Facebook had said that it had found that an operation likely based in Russian Federation spent $100,000 on thousands of USA ads promoting divisive social and political messages in a two-year-period through May. It also disclosed that the account for the news site RT, which the company linked to the Kremlin, spent $274,100 on its platform in 2016.
United States intelligence agencies said earlier this year that Russia had tried to sway the election in favour of Mr Trump but the Russian government and Mr Trump have both denied this. The search giant was also invited to testify before Congress on November 1 but has not yet said whether it has accepted the invitation. A study by the Oxford Internet Institute, which is affiliated with the British Oxford University, found that current and former USA military personal were especially targeted by the Russian disinformation campaigns.