A massive US-EU trade deal would harm the environment and consumer safety, Greenpeace said Monday citing secret documents it leaked, as Brussels dismissed the release as a "storm in a teacup".

The campaign group published 248 pages online to "shine a light" on the closed-door talks to forge a so-called Transatlantic Trade and Investment Partnership (TTIP), which would be the world's largest ever bilateral trade pact.

Greenpeace said the deal would place corporate interests above the environment and consumer safety, and inflict a dangerous lack of standards on US and European consumers.

"This treaty is threatening to have far reaching implications for the environment and the lives of more than 800 million citizens in the EU and US," said Greenpeace as it presented the documents in Berlin.

Washington and Brussels have been negotiating the mega-deal since 2013 and want it completed this year before US President Barack Obama leaves office, but it has faced mounting opposition on both sides of the Atlantic.

The European Commission, which negotiates trade deals on behalf of the 28 EU member states, said Greenpeace was "flatly wrong" in its interpretation of the documents.

"I am simply not in the business of lowering standards," said Trade Commissioner Cecilia Malmstroem in a blog.

"Many of today's alarmist headlines are a storm in a teacup," she said, adding that the papers "reflect each side's negotiating position, nothing else."

In Washington, the US Trade Representative said: "The interpretations being given to these texts appear to be misleading at best and flat out wrong at worst."

- 'Dark forebodings' -

In Europe there is deep suspicion that TTIP will erode ecological and health regulations to the advantage of big business with officials in France and Germany also increasingly voicing doubts about the deal.

Greenpeace said the papers show, for example, that the US wants to be able to scrap existing EU rules in areas such as food labelling or approval of dangerous chemicals if it they spell barriers to free trade.

"TTIP is about a huge transfer of power from people to big business," the group said.

The leak, a snapshot from ongoing talks, represents two-thirds of the TTIP draft text as of the latest round of talks in April, and covers a range of sectors from telecoms to autos to agriculture.

Germany's Sueddeutsche Zeitung daily said the documents "show that the opponents' fears are not unfounded ... They show that the reality of the negotiations is worse than these dark forebodings."

One of the many controversial demands is a refusal by the US to stop production of 17 American wines that use names protected in Europe, including Sherry, Chianti and Champagne.

Another controversial TTIP proposal is the goal to set up private investor courts that would allow multinational companies to sue governments if they deem public policy to hinder the terms of the deal.

- 21st century deal -

TTIP is billed as a free-trade deal for the 21st century, focused on harmonising regulations, lowering barriers on investment, opening access to government contracts and addressing new areas like data trade.

Last week, Obama and German Chancellor Angela Merkel made a joint pitch for TTIP, saying it would spur much-needed economic growth.

Following the latest negotiations last month, US and EU said they had made progress but "substantial work" remained to agree a deal in 2016.

They said that while 97 percent of tariff issues had been covered, three percent -- the most challenging, including for farm products -- remained.

French newspaper Le Monde, which also had access to the leaked documents early, said they showed that "the Europeans (are) more involved and more interested in negotiations" than the Americans, whose stance it described as "reluctant".

But the EU's chief negotiator Ignacio Garcia Bercero said he found it "difficult to understand" how anyone "came to the conclusion that the differences are irreconcilable based on the documents."

Greenpeace meanwhile decried the lack of mention at all in the proposed text of global goals to reduce greenhouse gas emissions.

"These leaked documents confirm what we have been saying for a long time," said Greenpeace EU director Jorgo Riss. "TTIP would put corporations at the centre of policy-making, to the detriment of environment and public health."

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