Donald Trump’s trade officials have accused Brussels of attempting to secure a “monopoly” for its meats and cheeses in South America as part of its blockbuster trade deal with Mercosur countries.

The EU and four South American countries will on Saturday sign a trade agreement, after negotiating for 25 years, which would cut almost all tariffs across a combined market of 700mn people.

But US officials have hit out at the deal for harming American farmers, barring them from selling produce that is tied to particular places in European countries, such as prosciutto di Parma, feta cheese and champagne.

“This is a blatant attempt to limit competition and export opportunities for non-EU suppliers to fairly trade in this large dairy and processed meat market,” said one US official familiar with the negotiations.

“The deal would basically give EU producers a monopoly for these products and would lock out producers from the US.”

The objections come as transatlantic trade tensions escalate between Washington and Brussels over the bloc’s slow pace in cutting tariffs and regulations following a limited trade deal agreed last year.

The Trump administration’s concern for its agricultural exports follows a $12bn bailout to US farmers last year after the sector was battered by the US president’s trade war.

The official said the US had repeatedly raised its concerns with countries including Brazil and the EU, which would secure protection for more than 340 named foods, as part of trade negotiations.

A trade negotiator for a Mercosur nation said that “geographical indication” for certain products was a long-running gripe for the Americans, but insisted they had not been contacted about the issue recently.

The complaints about the deal between the EU and Mercosur come as Washington makes an aggressive push to secure geopolitical influence across the western hemisphere as part of its so-called Donroe Doctrine.

In recent weeks Trump has launched a military operation to seize Venezuela’s leader Nicolás Maduro, and warned that Cuba, Colombia and Mexico could all be next in America’s crosshairs.

A majority of European member states backed the terms of the deal last week, despite widespread opposition from farmers, who claim that their counterparts in Mercosur operate with lower standards for animal treatment and pesticide use.

The deal represents a new push by the EU to secure lucrative trade agreements aimed at countering Trump’s aggressive protectionism and tariffs.

European Commission president Ursula von der Leyen made a veiled rebuke to Trump when EU member states approved it last week.

“At a time when trade and dependencies are being weaponised and the dangerous, transactional nature of the reality we live in becomes increasingly stark, this historic trade deal is further proof that Europe charts its own course and stands as a reliable partner,” she said.

She also shrugged off any idea the EU should stay out of the western hemisphere, adding it was “testament to the endurance and strength of our relationship with Latin America, and one that will bring us closer together”.

The Commission declined to comment. The US trade representative’s office declined to comment. Brazil’s trade ministry declined to comment.