Thousands of people rallied Saturday in the German capital against the massive free-trade accord being negotiated by the European Union and the United States.

Responding to a call by a group of political parties, trade unions and environmental and anti-globalisation groups, the demonstrators gathered at Berlin’s main train station for a march through the city.

Organisers said up to 100,000 people were expected to take part in the day of protest against the Transatlantic Trade and Investment Partnership (TTIP) under negotiation between Washington and Brussels, as well as a similiar deal with Canada.

Several trains and more than 600 buses had been chartered to transport protesters to the capital.

Talks on the pact between the US and 28-nation EU — which would be the world’s biggest trade deal if completed — began in 2013 and the two sides aim to conclude them by 2016.

Campaigners are particularly angered over Washington’s insistence that as part of the pact, private companies be allowed to sue governments before special tribunals.

Some of the placards waved by demonstrators in Berlin read “Stop TTIP” and “TTIP signals climatic shipwreck”.

Several political and union leaders were to address the rally later in the day.