Thousands of demonstrators have marched at the European Union headquarters to protest trans-Atlantic trade talks with the United States and a planned deal with Canada, claiming they would hurt labor and consumer rights while undermining environmental protection.

Representatives of unions, social organizations, human rights and farming groups snarled evening rush-hour traffic in the heart of the Belgian capital hoping the talks with Washington on the so-called TTIP trade deal fail to get enough European backing.

They also hope there will be enough of a groundswell of opposition to make sure that the CETA deal with Canada doesn't get the necessary parliamentary approvals in EU member states.

Backers of both deals say that they will be essential in boosting trade and jobs in the future.