The artists, who go by the name kennardphillips, have accused advertising companies JCDecaux and CBS Outdoor of “political censorship” in refusing to carry it.
The two firms controlled between 50%-70% of the outdoor advertising market in 2011, according to a government report.
CBS Outdoor said the poster was refused after consultation with the Committee of Advertising Practice, which advises firms on whether ads may breach its code of conduct.
Neither gave details of which part of the code it breached, but the code includes rules forbidding ads that are misleading and are likely to cause “serious or widespread offence”.
Kennard and Phillips said CBS Outdoor had told them they could not use images involving explosions on public transport, such as on the sides of buses. JCDecaux declined to comment.