White supremacist groups in the US have been creating and selling racist computer games with titles like "Ethnic Cleansing" and "Shoot the Blacks," according to a report out this week from the Anti-Defamation League.
Abraham Foxman, ADL's national director, said the groups were both creating racist games using open source software and modifying commercially available games to make targets of particular ethnic groups.
Mr Foxman said: "The difference is these games are loaded with blatantly racist messages and themes.
"It's a disgusting, sick perversion of the original games, where the manipulated versions give players points for killing as many non-whites and Jews as possible."
One of the games, Ethnic Cleansing, is advertised as the "most politically incorrect video game ever made."
Players kill black and Hispanic characters before descending into a subway station "where the Jews have hidden".
Black characters make monkey and ape noises when shot. The advertisement continues: "Then if your (sic) lucky you can blow away Jews as they scream 'Oy Vey!' on your way to their command centre."
Ethnic Cleansing is produced by Resistance Records, the publishing arm of the National Alliance, a white supremacist group, and retails for $14.88 (£10.50).
Repeated attempts by the Guardian today to access the Resistance Records website failed.
According to the ADL, Ethnic Cleansing was released last month on the US national holiday to celebrate civil rights leader Martin Luther King Jr.
Adverts on the site read: "Celebrate Martin Luther King day with a virtual race war!"
The group reportedly has plans to produce another game based on the Turner Diaries, a white supremacist novel by the leader of the National Alliance, William Pierce.
Other games highlighted by the ADL include scenarios that allow players to run a concentration camp, available on the website of the World Church of the Creator, which describes itself as a group for "white liberation".
Jon Dovey, a professor who studies gaming at the University of the West of England, said it was important to keep in mind that these games were a small part of the online community, and that action against them is possible.
"I'd recommend people to go to these sites and flame it, bombard it to bring it down. It's online direct action, and it's not difficult to do," he said.