United States and European negotiators are struggling over food safety and environmental regulations in the controversial trade deal championed by President Obama, according to leaked documents released Monday by Greenpeace – an opponent of the deal.

Advocacy groups argue the hundreds of pages of documents show negotiations around the Transatlantic Trade and Investment Partnership (TTIP), which has been conducted in a series of highly secretive meetings, may be about to collapse.

"The TTIP negotiations will never survive this leak," John Hilary, the executive director of antipoverty group War on Want, told The Independent. "Now we can see the details for ourselves, and they are truly shocking. This is surely the beginning of the end for this much hated deal."

The US Trade Representative's office said that it would not comment on the "validity of alleged leaks," but a spokesman told Reuters that "the interpretations being given to these texts appear to be misleading at best and flat-out wrong at worst."

The trade negotiations have sparked a series of protests, including most recently in Hannover, Germany – where Chancellor Angela Merkel has publicly pledged her support for the TTIP – last week.

The documents show the US trying to push its own approach to environmental protections over the more expansive rights granted to EU citizens, Greenpeace says.

"It is time to shine a light on these negotiations. Hard won environmental progress is being bartered away behind closed doors. These documents reveal that civil society was right to be concerned about TTIP. We should stop the negotiations and start the debate," says Faiza Oulahsen, a campaigner for Greenpeace Netherlands, in a statement.

For example, none of the documents' 13 chapters mention the "precautionary principle," a European Union concept that governs how potentially harmful products are sold, Greenpeace says.

But according to the conservation group EcoLogic, "The characteristic feature of the precautionary principle is risk prevention in the face of scientific uncertainty. The precautionary principle aims to prevent harm before a hazard has come into existence."

The US, by contrast, uses what environmental groups say is a weaker approach that attempts to minimize the risks from potentially harmful products rather than avoid them entirely. If the deal moves forward, Britain and Europe might be forced to adopt that approach, The Independent reports.

The leaked documents also don't appear to make reference to the landmark Paris climate deal to cut CO2 emissions and limit temperature increases to 1.5 degrees C., Greenpeace says. That appears to go against the European Commission's stated commitment to addressing climate issues in future trade deals.

But European regulators say the "consolidated texts" released by Greenpeace reflect the current position of each side, not the final outcome of the deal.

"It is only normal that both parties in a negotiation want to achieve as many of their own objectives as possible," writes Cecilia Malmström, a Swedish politician who serves as European Commissioner for Trade in a blog post Monday.

"That does not mean that the other side gives in to those demands.... In areas where we are too far apart in a negotiation, we simply will not agree. In that sense, many of today's alarmist headlines are a storm in a teacup."

A publicly available document released in February does include a reference to the precautionary principle, Ms. Malmström writes.

But for environmental groups and some lawmakers, the secrecy surrounding the negotiations has been a long-running concern. Another issue is the influence of industry groups over the deal.

"The leaked documents indicate that the EU has not been open about the high degree of industry influence," Greenpeace says its statement.

While the EU's public reports only briefly mention discussions with industry groups, the group says, the leaked documents often mention consultations with such groups, including the chemical industry.

In Germany, skepticism about the deal has also cut across party lines and increased dramatically over the past year. One nationwide poll found that only 17 percent of Germans consider the deal a good thing, compared to 55 percent in 2014, as the negotiations began.

The high levels of secrecy – previously, German lawmakers could only review pages of the deal in a specially designated room under strict conditions – has also frustrated Sigmar Gabriel, Ms. Merkel's economy minister, Time reports.

"We are adult citizens. We are adult democracies," he told US Secretary of Commerce Penny Pritzker, during a panel discussion in Hannover last week. "It must be possible to allow somebody to look" at what's already been agreed, he added, noting that the secrecy around the talks "creates mistrust."

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Citing the revelations in the documents, Greenpeace is pushing for a more open approach, arguing that a complete version of the treaty text should be immediately released.

"Whether you care about environmental issues, animal welfare, labor rights or Internet privacy, you should be concerned about what is in these leaked documents," says Ms. Oulahsen of Greenpeace Netherlands. "We call on all elected representatives and other concerned parties to read these documents and engage in the debate."