"The first thing we teach all of our members is: 'Don't accept the first offer, always go into negotiation with them, '" she says.

WSJ: Downturn's Ugly Trademark: Steep, Lasting Drop in Wages

The French economy minister Laurent Fabius said that "no European" could accept such a clause, as it implies a pre-determined end-point for the negotiation.

BBC: Progress at trade deal talks