In the song Wamp Wamp (What It Do), American rapper Malice refers to a Jew who is a "tightwad". Malice, with his brother Pusha T, comprises the acclaimed hip-hop duo The Clipse. Since they specialise in overblown stories of crime escapades, the "tightwad" line is fairly tame in comparison to much of their other material, but it still stands out as a stark example of casual antisemitism.

And The Clipse are not the only ones. Several other high-profile rap artists have made derogatory references to Jews. Ghostface Killah raps about "doing business with Jews". When Ice Cube released the song No Vaseline in the '90s, he accused his former group N.W.A of "letting a white Jew tell you what to do." Even Mos Def, one of the more progressive rappers currently recording, refers to a "tall Israeli running this rap sh-t."

The tall Israeli in question is Lyor Cohen, the Jewish head of Warner Music Group and formerly of hip-hop label Def Jam Records (where he oversaw artists like Ghostface). He is one of a number of high-powered hip-hop industry figures who are Jewish, including legendary producer Rick Rubin, Koch Records head Alan Grunblatt and Eminem manager Paul Rosenberg. These executives are rarely, if ever, heard to criticise their artists over antisemitism in lyrics.

Joe Berkowitz, a Brooklyn-based journalist who has written extensively about hip-hop culture, notes that an atmosphere of permissiveness surrounds some rap artists, one that does not exist in other areas of the music business.

"A lot of statements are constantly being made about different groups of people in hip-hop," he says. "If it was blatant and clearly coming from a place of hate, there would be censorship and people would come out against it. But it seems as if you can get away with being casually antisemitic, especially if it's done in a funny way or used as part of a punchline."

Outside music, however, it is a different matter. Professor Griff of seminal rap crew Public Enemy came under fire for making antisemitic comments in a 1989 media interview, and was fired from the group as a result. Griff later apologised for his comments.

Clearly, music provides some sort of safe zone for artists. Berkowitz suggests that rappers are often allowed to push the boundaries of what is acceptable and, in that context, the instances of antisemitism are not sufficiently upsetting to provoke the anger of powerful industry figures.

"There hasn't been a big litmus test for what, in the lyrics, is too much. Little bits will get by," he says.

The simple explanation may be that for many of these executives, it is profitable to ignore the lyrical excesses of their artistes. Some hip-hoppers revel in their outlaw image, and fans expect a certain shock value to the lyrics. (Indeed, it is not just Jews who take flack - other ethnics groups have been targeted and, of course, the portrayal of women and gay people remains an issue.) So it is often not in the interests of the record executives to tone down the content.

But then there is the other end of the scale - Jewish rappers themselves.

From Beastie Boys to 3rd Bass to more contemporary artists like Etan G, Alchemist and Remedy, hip-hop has no shortage of Jewish talent. However, very few have tackled the issue of antisemitism among their non-Jewish peers.

Antithesis, born Samuel Green, is a London-born rap artist who styles himself "The Zionist Rapper" and recently relocated to Israel. He insists that antisemitic content in lyrics has barely registered with him.

"I've got to be honest with you," he says, "it's not something I've really noticed - and I do listen to a lot of hip-hop. Obviously, if I did hear it, it wouldn't sound nice. Racism is not a good thing, and should never be encouraged."

But surely Jewish rappers have a responsibility to speak out against antisemitic content?

"There are a lot of Jews involved in the scene," says Antithesis. "It's weird that they implicitly endorse this stuff. I can't imagine myself as a Jewish guy not having something to say if I heard it."

Whatever the level of response, there have been occasional signs that rappers and audiences are aware of the problems.

Jay-Z, one of rap's most successful and influential artists, and Russell Simmons, the co-founder of the Def Jam record label, joined forces in 2006, to broadcast a television commercial condemning antisemitism and equating it with racism, and urging viewers to speak out against it under the slogan: "We are one".

The effect was somewhat spoiled by the fact that Jay-Z is not averse to questionable references to Jews in his own lyrics - most notably in the song This Can't be Life, in which he raises the stereotype of alleged Jewish meanness by rapping that his "flow is tight like [he] was born Jewish".

But Berkowitz thinks that listeners are becoming more discriminating.

"More people are listening carefully and taking what they hear seriously. I feel that a rap artist is more likely to get in trouble for saying the wrong thing these days."

Even so, Berkowitz himself feels that the low-level antisemitism in hip-hop, of the kind expressed in songs by Jay Z and The Clipse, does not merit censorship or public outcry - rather it is something that, he believes, one has to approach with a sense of humour.

"As a Jewish hip-hop fan, I decided it wasn't worth getting upset. If I did that, I would have to get upset on behalf of everyone, not just my personal ethnic group that might bear the brunt some of the time. But if the antisemitism was blatant, or a rapper made a radically offensive statement, of course it would certainly be worth taking action over."