A top US lawmaker has urged the UK culture secretary to detail her plans to give big social media companies greater prominence to trusted news sites, as American authorities push back against perceived attacks on free speech in Europe.

In a letter to Lisa Nandy, Jim Jordan, chair of the House Judiciary Committee, warned that the proposals risked creating a “tiered information system” and called for a formal briefing by July 28, when a new culture secretary is likely to be in post under presumptive prime minister Andy Burnham.

The UK Government announced plans to give established broadcasters such as the BBC, ITV and Channel 4 more promotion on platforms such as Instagram, You Tube and Tik Tok, amid concerns about online misinformation. US officials have offered grants of up to $3mn for groups that combat “censorship” and develop “civilisational bonds” between the US and the continent.

UK sources say the policy isinjured to ensure access to “trustworthy information from a range of news providers” and will be decided in an open and transparent manner with regard to protecting media freedom. The UK media green paper consultation will engage stakeholders on the criteria for a trustworthy news provider.