The European Union and the United States reject claims that a trade agreement they are negotiating would lower consumer protection in Europe, arguing that newly leaked documents do not reflect the final deal.
The environmental group Greenpeace on Monday published 248 pages of confidential documents on the Transatlantic Trade and Investment Partnership, claiming they showed US efforts to circumvent EU consumer protections and calling for negotiations to be scrapped.
If finalized, TTIP would create the world's largest free trade area with 800 million people. Opponents fear the deal could water down standards and give corporations more clout.
The talks are being held behind closed doors "with the intention of creating a powerful battering ram that can eliminate even the most firmly established climate and consumer protections," Juergen Knirsch of Greenpeace said in Berlin at the annual technology conference re:publica.
He called on the European Commission - which is leading negotiations on behalf of the EU - to "press the restart button" on a deal that is "beyond redemption."
EU Trade Commissioner Cecilia Malmstrom rejected many of the accusations, saying the leaked documents only show the differing negotiating positions of the EU and the US, not the final agreement.
"In areas where we are too far apart in a negotiation, we simply will not agree," Malmstrom wrote in a blog post. "No EU trade agreement will ever lower our level of protection of consumers, or food safety, or of the environment."
The US trade representative called the leaks "misleading at best and flat out wrong at worst."
"TTIP will preserve, not undermine, our strong consumer, health, environmental standards, and position the US and the EU to work together to push standards higher around the world," Michael Froman said in a statement.
"We look forward to having a fact-based discussion about what TTIP seeks and does not seek to achieve."
The documents - initially shared with media outlets including the German daily Sueddeutsche Zeitung and public broadcasters WDR and NDR - detail how the US is pressuring the bloc to buy more of its agricultural products, according to Greenpeace.
According to the group, the US is bargaining to weaken EU restrictions on genetically modified organisms and hormone-treated meat. TTIP, it says, would do away with the bloc's precautionary principle, which obliges regulatory caution when there is scientific doubt over a product's suitability for human consumption.
The EU's chief negotiator, Ignacio Garcia Bercero, denied the claim, which he said is "nowhere" in the documents.
"We are fully maintaining the precautionary principle," Garcia Bercero said in Brussels.
Activists have long called for the release of all TTIP texts. The EU has taken steps to improve transparency, but officials on both sides of the Atlantic have stressed the need to keep negotiations secret to strike the best deal possible.
The leak would be investigated, Garcia Bercero said, noting that Washington had expected the EU to protect the confidentiality of the talks.
"All negotiations with a third country need to take place on the basis of mutual confidence," he said.
Garcia Bercero was in New York last week for the 13th round of negotiations since the TTIP talks were launched in 2013.
On Friday, both sides expressed hope of completing TTIP this year, despite US elections in November and a British vote in June on whether to stay in the EU. The deal has faced public opposition on both sides of the Atlantic.
US President Barack Obama, who leaves office in January, has made trade a key part of his remaining agenda.
Spokesman Josh Earnest said the White House is "not concerned" about the leaks and expects no "material impact" on the agreement. He emphasized that Obama is seeking a trade deal that would strengthen standards.
"Our focus is on trying to complete these negotiations by the end of the year," Earnest said.