Posters with the phrase "America's latest hero is a Muslim straight out of jail" has been banned from the Tube by London Underground (LU).
LU said it will not show the posters from a £1m advertising campaign for new TV series Sleeper Cell until creators remove the word Muslim from the text.
It claims it will offend people and it is trying to be sensationalist.
A spokesman for the digital channel FX series said it had consulted with the Advertising Standards Authority (ASA).
He said the poster was meant to sum up the show's plot and would still appear in newspapers.
"It is in no way intended to cause offence or upset to Muslims," the FX spokesman said.
"We ran the creative by the ASA who advised us we were not in breach of the British Code of Advertising so it has come as a real surprise that the London underground have refused to run it."
The channel described the show, starring Michael Ealy as FBI agent Darwyn Al Sayeed, as the first American drama to feature a Muslim as the lead heroic character.
The character poses as a prisoner in order to infiltrate a fundamentalist group.
An LU spokeswoman said: "Following consultation with Viacom, who manage advertising on the Tube, it was decided to ask for the words 'is a Muslim' to be removed.
"This decision was taken in line with our standard policies, which seek to avoid gratuitously insulting large groups of Londoners."
An ASA spokesman said: "If London Underground wants to do this, it is entirely at its discretion."
This link directs to the official "Sleeper Cell" page and contains a brief clip. This link gives a short description of the program.