Some of the world's largest technology and telecoms companies are helping to fund "free-market thinktanks" pushing radical right-wing policy agendas in the US, according to a recent report by a watchdog group.

An investigation by The Center for Media and Democracy (CMD) and Progress Now revealed that contributors to State Policy Network (SPN), a shadowy group of lobbyists operating in all 50 states, included Facebook, Microsoft, Time Warner, AT&T and Verizon.

The report refers to SPN as an "$83 million right-wing empire" that pushes an "extreme right-wing agenda", with policies that include advocating reductions in labour protections and minimum wage, privatising education, blocking healthcare reform, opposing climate change regulations and creating a tax system that benefits those at the very top level of income.

Executive director of the CMD Lisa Graves said: "The 'experts' of State Policy Network groups get quoted on TV, in the papers, or in the legislature as if they were nonpartisan, objective scholars on issues of public policy.

"But in reality, SPN is a front for corporate interests with an extreme national policy agenda tied to some of the most retrograde special interests in the country, including the billionaire Koch brothers, the Waltons, the Bradley Foundation, the Roe Foundation, and the Coors family."

Denise Cardinal, executive director of Progress Now, added that these organisations were "of the rich, by the rich, and for the rich", falsely portraying themselves as representing everyday, working class Americans.

"It's just a blatant lie," Cardinal said. "What we're doing is trying to bring some transparency to the damaging work they're doing on a daily basis.

"From policies that promote polluting the air and water to the destruction of our public education system and a tax system that benefits their rich donors, what these organizations are doing is shameful and it's time that someone brought this to light."