PARIS — The journalist who started France’s equivalent of the #MeToo social media campaign against sexual harassment is being sued for defamation by the man she had accused of making salacious and disrespectful comments about her.

Sandra Muller, a French journalist working in New York, started the hashtag BalanceTonPorc, or ExposeYourPig, in October with a series of posts on Twitter that encouraged women to speak out against sexual harassment and that accused a former television executive of having made humiliating advances toward her.

The former executive, Eric Brion, has not denied the advances but argued that she was wrong to characterize them as sexual harassment.

Tens of thousands of women in France adopted Ms. Muller’s hashtag to recount their own experiences, spurring a debate on gender relations and sexual norms. Most recently, a letter signed by the actress Catherine Deneuve and scores of other women to denounce the #MeToo and #BalanceTonPorc movements set off a strong backlash.