In a statement issued yesterday, US secretary of state Marco Rubio said the five individuals “have led organised efforts to coerce American platforms to censor, demonetise, and suppress American viewpoints they oppose”.

“These radical activists and weaponised NGOs have advanced censorship crackdowns by foreign states — in each case targeting American speakers and American companies,” he claimed.

“As such, I have determined that their entry, presence, or activities in the United States have potentially serious adverse foreign policy consequences for the United States.”

While the State Department did not initially name the five individuals, they were later identified as Mr Breton alongside Anna-Lena von Hodenberg and Josephine Ballon of the German NGO HateAid, Clare Melford of the UK-based Global Disinformation Index, and Imran Ahmed, a Briton who serves as chief executive of the US-based Center for Countering Digital Hate.

All have been involved in efforts to tackle online hateful speech, misinformation and disinformation.

Mr Rubio said: “President Trump has been clear that his America First foreign policy rejects violations of American sovereignty. Extraterritorial overreach by foreign censors targeting American speech is no exception.

“The State Department stands ready and willing to expand today’s list if other foreign actors do not reverse course.”

Responding on social media, Mr Breton said: “Is McCarthy’s witch hunt back?

“As a reminder: 90 per cent of the European Parliament — our democratically elected body — and all 27 Member States unanimously voted [for] the DSA.

“To our American friends: ‘Censorship isn’t where you think it is.’”