The European Commission says it will consult on part of a far-reaching EU-US free trade deal amid concern that hard-won social protections in Europe might be undermined.
The trade negotiations began last year but now the Commission has launched a three-month public consultation on the proposed investment rules for firms.
There are fears that they could give big firms too much power to block unfavourable government policies.
Negotiations will continue.
The proposed EU-US Transatlantic Trade and Investment Partnership (TTIP) could bring huge benefits for Europe and America, the Commission says.