Protesters will descend on a McDonald's outlet in London's Leicester Square at noon on October 16 to hand out anti-McDonald's leaflets and call for the firm to stop marketing its food to children.
Dave Morris, one of the McLibel defendants, told PRWeek that anti-fast-food campaigners had lost all faith in "government bodies or corporations to take any effective action to improve the situation as regards obesity".
Morris said grassroots activism was the only way to successfully challenge fast-food firms over such issues.
Referring to the government's unwillingness to clamp down on marketing fast food to children as a "scandal", he described Saturday's anti-McDonald's protests as part of a "bigger jigsaw" of global anti-capitalist sentiment.
McDonald's pre-tax profits slumped from £83.8m in 2002 to £23.6m last year.
Last month, the McLibel case reached the European Court of Human Rights in Strasbourg with a verdict still pending.
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