Twitter is rushing to reassure advertisers that it will remain a safe place for brands after Elon Musk takes over the company, as the campaign groups that organised a Facebook advertising boycott in 2020 warn the Tesla chief’s focus on freedom of speech could increase toxicity and abuse.

The San Francisco-based company has written to agencies in the wake of Monday’s $44bn deal announcement, insisting the company remains committed to ensuring their ads are not placed alongside harmful or offensive content, according to an email seen by the Financial Times.

That outreach reflects concern that Musk’s stated position as a “free speech absolutist” could hurt Twitter’s $4.5bn-a-year advertising business built around the social media platform being attractive to traditional marketers.