An unprecedented drive to lobby ministers to ditch strict EU safety standards in order to secure a US trade deal is being drawn up by a transatlantic group of conservative thinktanks, it has emerged.

Organisers of the self-styled “shadow trade talks”, which are set to include 10 leading rightwing and libertarian groups from the UK and the US, are preparing to push their “ideal free trade agreement” that would allow the import of US meats, drugs and chemicals banned in Britain.

The conservative groups involved include the Heritage Foundation, which has pushed for the lifting of environmental protections, and the Cato Institute, co-founded by billionaire oil barons Charles and David Koch. In Britain the project is being overseen by the Initiative for Free Trade (IFT), an organisation founded by the hard-Brexit advocate and Tory MEP Daniel Hannan.

According to a document outlining the project, mistakenly published online by the IFT, the groups will “hash out an ‘ideal’ US-UK free trade agreement (FTA)” that includes Britain recognising US standards which are widely seen as weaker than those adopted by the EU. Such a move would allow imports of chlorinated chicken and hormone-reared beef to be sold in the UK for the first time.

“An ideal US-UK FTA would focus on mutual recognition of standards and qualifications for goods and occupations,” states the document, which was uncovered by Greenpeace’s investigative unit. “IFT wants to show policymakers what the potential gains are from such a deal, so that the final agreement ends up being somewhere close to the ideal.

“US exporters of agricultural produce – beef, for instance – would have a brand new market to sell to, and British consumers a cheaper alternative to the current options.”

It also advocates tearing up the EU’s “precautionary principle”, under which traders have to prove something is safe before it is sold, rather than waiting for it to be proved unsafe. The project will include two rounds of mock trade negotiations among figures from the 10 groups. The document even claims that a civil servant from Liam Fox’s department for international trade will attend. The department said it had never heard of the initiative and had not received an invitation.

Greenpeace UK’s policy director Dr Doug Parr said: “This network of secretive pressure groups is trying to hijack US-UK trade talks to impose its anti-regulation agenda. They want a free-for-all Brexit that waters down rules on food safety, animal welfare and nature protection. It’s the exact opposite of the green vision promised by Theresa May.”

A spokesperson for the IFT said the plan was an internal document not meant for public consumption.She said it was not a solely “libertarian” campaign, as some of the thinktanks involved were conservative.

“We don’t hope to pressure the government to do anything,” she said. “We hope to provide government with as much information as possible on the potential gains of such a UK-US trade deal.

“Mutual recognition of standards, which we do mention quite a bit, would not require the UK to move away from the precautionary principle at all, or to change its standards, regulations or laws in any way.

“If consumers don’t want to buy products made to different standards to our own, they will see the US flag on the packet and not buy it,” she said.