Some 200 protesters gathered in Hanover on Sunday to demonstrate against the Transatlantic Trade and Investment Partnership (TTIP) being negotiated between the US and the European Union, as US President Barack Obama arrived in the city.
Organizers said they had expected considerably more people to turn out to protest against the planned free trade agreement that has drawn criticism on both sides of the Atlantic.
The protest started in the centre of the city and moved to the Congress Centre where Obama was to open the Hanover industrial trade fair with Chancellor Angela Merkel on Sunday evening.
Police in the city said that as many as 35,000 people had gathered in Hanover on Saturday to protest against the planned agreement.
Opponents of the deal fear that it will undermine standards and have accused negotiators of a lack of transparency in the talks.