Netflix apologised for a reference to "Sunday Bloody Sunday" in a promotional tweet for the new series of Chilling Adventures of Sabrina.
The caption, which was removed, was posted with images of cast members, including star Kiernan Shipka, spattered by fake blood.
Fans said offence could be taken because the phrase refers to the 1972 Bloody Sunday killings in Northern Ireland, in which 13 people lost their lives and 15 people were wounded after members of the British Army's Parachute Regiment fired on civil rights demonstrators. The day became known as one of the darkest during the Troubles.
Sunday Bloody Sunday is also the name of a song on U2's 1983 album War, which spoke of the unrest in Northern Ireland.
In a statement, the streaming service said: "Our tweet was unacceptable and has since been removed.
“We are very sorry for the hurt and distress it caused.”
The fourth and final season of Chilling Adventures of Sabrina was released on the streaming platform at the end of 2020.
The show explores the origins of Sabrina the Teenage Witch, and follows on from the popular 1990s show starring Melissa Joan Hart.