Some commentators argued that sexual harassment accusations would be better handled in a courtroom than on social media. “Denouncing sexual harassment on a social network with a hashtag isn’t the appropriate place at all,” said Christophe Noël, a labor lawyer. “It can rebound on the accuser and create an open door to excesses and defamation.”

Ms. Muller, the journalist who first tweeted the “Expose Your Pig” hashtag, said in a phone interview on Tuesday that although she was overwhelmed by the hundreds of reactions she had received, she didn’t want Twitter to become a tribunal. “I’m not a judge,” she said.

Two lawyers for the executive Ms. Muller named in her tweet demanded on Tuesday that she delete it; one of the lawyers, Nicolas Bénoit, called her accusation a case of defamation but declined to comment further. The executive didn’t respond to requests for an interview.

In France, the Weinstein affair has recalled the case of Dominique Strauss-Kahn, the former International Monetary Fund chief and one-time presidential contender who was arrested in New York in 2011 and accused of assaulting a hotel housekeeper. Those charges were dropped, but helped dent a longstanding French reluctance to breach the privacy of public figures, no matter their sexual transgressions.

Sandrine Rousseau, a former leader of the French Green Party and leading advocate for victims of sexual harassment, said the Weinstein case had particular resonance in France because women had suffered in silence for so long.

Ms. Rousseau was one of a dozen women who in 2016 accused a Green Party legislator, Denis Baupin, of sexual harassment, saying he had pushed her up against a wall and kissed her against her will. Mr. Baupin, who resigned as vice president of France’s National Assembly, denied the accusations and the case was dropped on the grounds that too much time had elapsed.