A Republican Congressman is asking leading tech companies for evidence that Russia bankrolled ads opposing hydraulic fracturing, a contentious energy extraction process that has split American politics.

In letters to Alphabet Inc, Facebook and Twitter, Texas Republican Lamar Smith demanded documents that could illuminate if Russia sought to use “social media to influence the US energy market”, further widening a probe of how Russia used prominent technology platforms to disrupt the 2016 election and sow discord. Among the information he requested was anything “relating to the source of advertisements…advocating for so-called green initiatives”.

“The Committee is concerned that divisive social and political messages conveyed through social media have negatively affected certain energy sectors, which can depress research and development in the fossil-fuel sector and the expanding potential for natural gas”, the letter says.

Silicon Valley is facing a reckoning as lawmakers seek to unravel a concerted Russian effort to influence the previous election. Facebook has turned over to Congress some 3,000 ads that the social media giant concluded were launched by fake Russian-linked accounts. Many of those ads sought to widen fissures in the American electorate with divisive messages about topics like race and immigration, Facebook has said. The company said in an update this week that “it's possible” it could uncover more ads generated by Russian-directed fake accounts.

But the effort by Rep Smith - a fossil fuel industry ally who has cast doubt on the scope of manmade climate change and assailed climate scientists - extends the line of inquiry from election integrity to the politically charged issue of fracking. The technique - which involves blasting a mix of water, sand and chemicals underground to dislodge natural gas and other fuels - has long divided policymakers.

Many environmentalists and Democrats view it as a hazard to drinking water and public health, and a push to ban the process has energized grassroots liberals for years. Proponents defend it as a source of jobs and a route to American energy independence. Rep Smith is firmly in the pro-fracking camp.

How fracking works and where it could happen Show all 2 1 /2 How fracking works and where it could happen How fracking works and where it could happen Fracking: How It Works How fracking works and where it could happen Fracking Map UK

In his letters, Rep Smith wrote that “Russia’s meddling in the U.S. energy market is well documented in the public domain”, saying the country was funding “a covert anti-fracking campaign to suppress the widespread adoption of fracking”.

As evidence, Rep Smith cites a New York Times story about Eastern European elected officials suspecting Russia’s involvement in anti-fracking protests; former United Nations Secretary-General Anders Fogh Rasmussen’s 2014 remark that Russia had worked with “environmental organisations working against shale gas to maintain European dependence on imported Russian gas”, citing “allies” who told him so; and a declassified report on Russian election interference detailing Russian broadcaster RT’s “anti-fracking programming”.

“This is likely reflective of the Russian Government's concern about the impact of fracking and US natural gas production on the global energy market and the potential challenges to Gazprom’s profitability”, the report says, referencing a Russian energy company that is a pillar of the country’s economy.

How Fracking works

This is not the first time Rep Smith has targeted what he calls Russian attempts to undermine the energy market. In June, he wrote Treasury Secretary Steve Mnuchin asking for a full investigation.

But by demanding information from technology companies, Mr Smith is adding a new - and potentially deeply partisan - dimension to a debate over how the gatekeepers of information that reaches millions of users police their content.

In addition to the revelation that thousands of apocryphal Russian ads were allowed to circulate on Facebook, tech companies have been on the defensive amid a string of media reports finding that ad purchasing tools allowed companies to target paid content to racist and anti-Semitic subgroups.