One brave Greenpeace member hung from a crane to present his poster

waved flags, carried placards saying 'Yes We Can - Stop TTIP!'

Thousands of demonstrators gathered in Germany to protest a planned free trade agreement between the U.S. and the EU, a day before President Barack Obama arrives.

The streets of Hannover were crawling with activists who bitterly oppose the Trans-Atlantic Trade and Investment Partnership, or TTIP.

Demonstrators waved flags and carried placards with slogans such as 'Yes We Can - Stop TTIP!' and one brave Greenpeace member hung from a crane to present his poster high in the sky.

Scroll down for video

Thousands of demonstrators gathered in Germany to protest a planned free trade agreement between the U.S. and the EU, a day before President Barack Obama arrives

The streets of Hannover were crawling with activists who bitterly oppose the Trans-Atlantic Trade and Investment Partnership, or TTIP

A man on stilts and dressed like the Statue of Liberty walks in front of balloons forming the slogan Stop TTIP during the protest

Organizers claimed that 90,000 people attended the demonstration in Hannover but police estimate the count was more like 30,000.

Obama will open the world's largest industrial fair in the northern German city on Sunday, leading a delegation of American companies hoping to conquer new markets abroad.

He'll also be trying to complete the trans-Atlantic trade pact, which is one of his presidency's main pieces of unfinished business.

Proponents of the agreement argue that lowering tariffs and harmonizing rules would give a much-needed boost to businesses at a time of global economic uncertainty.

Or as Obama put it when the talks launched three years ago: 'New growth and jobs on both sides of the Atlantic.'

But critics worry that it would erode consumer protection and environmental standards.

Demonstrators waved flags and carried placards with slogans such as 'TTIP no thanks!'

An activist of the environment organization Greenpeace with a banner reading ' Yes we can stop TTIP!' hung from a building crane to show off his poster

The streets of Hannover were crawling with activists who worry that TTIP is a deal favouring only big business

Opponents of a proposed transatlantic trade deal (TTIP) hold a banner reading 'Don't give TTIP any chance. Stop TTIP, CETA, TISA' during a prostest rally on the eve of U.S. President Barack Obama's visit

Protestors demonstrate against the Trans-Atlantic Trade and Investment Partnership (TTIP) free trade agreement

Officials in Washington and Brussels are trying to clinch key parts of the deal before the end of the year, after which a new U.S. president and election campaigns in major European countries could complicate negotiations.

The discussions, due to resume on Monday in New York, have come under criticism for the secretive manner in which they've been conducted.

National lawmakers are only allowed to view draft documents in special reading rooms and are forbidden from talking about the documents with experts, the media or their constituents.

Proposals to create dispute settlement tribunals have also stoked fears.

EU trade chief Cecilia Malmstrom envisages special investment courts that would rule in disputes between governments and companies that feel they face undue legal hurdles to their business.

Officials in Washington and Brussels are trying to clinch key parts of the deal before the end of the year

The discussions, due to resume on Monday in New York, have come under criticism for the secretive manner in which they've been conducted

Critics say such courts could place the interests of corporations above those of democratically elected governments, citing a recent case where tobacco giant Philip Morris sued Uruguay over a law requiring graphic warnings on cigarette packages.

Alfred de Zayas, an American law professor and U.N. human rights expert, argues that such courts are unnecessary in countries that abide by the rule of law, such as the United States or the EU's 28 nations.

Backers of the special courts say they would prevent cases from being heard by American jurors who don't understand the complexities of international trade law, and ensure that U.S. companies don't face discrimination in European countries with high rates of corruption.

Juergen Hardt, a German lawmaker, said the protesters 'also want to incite anti-American feelings'

Protesters carried placards and waved flags with slogans such as 'Yes We Can - Stop TTIP!'

A man holds a United States flag with the slogan 'For America Against TTIP' during the protests in Hannover

Juergen Hardt, a German lawmaker and the government's coordinator for trans-Atlantic cooperation, believes some of those leading the fight against TTIP 'have other motivations' beyond trade.

'They also want to incite anti-American feelings,' he said.

A protester holds a placard with pictures of German Chancellor Angela Merkel and U.S. President Barack Obama

The EU's executive branch is trying to promote the benefits of a deal.

On its website, it suggests that TTIP will boost demand for European delicacies like cheese, hams, wine, olive oil, spirits, and chocolate.

'High tariffs at U.S. customs — up to 30 percent — make some of these hard for Americans to afford — and difficult for European farmers and firms to export,' it says.

TTIP's backers hope images of Obama in Europe — where his popularity remains high — will counter those of tens of thousands protesting the deal.

In her weekly video message Saturday, Chancellor Angela Merkel said everything has been done to improve the transparency of the negotiations — within reason.

And she stated anew that European standards won't be eroded.

'We are not falling behind our standards, but securing those we have in Europe today on the environment and consumer protection,' she said.

Yet time may be running out for a deal. A spokesman for Germany's Economy Ministry said that no draft proposals have been exchanged about numerous areas of negotiation.

The two sides are also divided about the issue of tariff reductions and the opening up of the markets for services and procurement.

'In order to achieve negotiating success this year, it will be crucial to make significant progress by the summer on technical questions, so that the final negotiations are restricted to a few, politically sensitive areas,' said Andreas Audretsch, the ministry spokesman.

In her weekly video message Saturday, Chancellor Angela Merkel said everything has been done to improve the transparency of the negotiations