Controversial Simpsons opening by graffiti artist Banksy

New York: The always clever and often subversive opening sequence for The Simpsons took a darker-than-usual turn with Sunday's episode, depicting the animation process for the Fox cartoon series as sweatshop drudgery performed by an exploited Asian underclass.

Created by the street artist and activist Banksy, the sequence began with the sight of hometown Springfield covered with graffiti - and tagged by Banksy himself.

Then, when the Simpson family gathers on their living room couch, that image becomes a reference shot for legions of workers in the grim industrial complex where they paint cartoon cells and churn out Simpsons merchandise (including Bart dolls stuffed with the fur of kittens tossed into a wood chipper, and DVDs whose center holes are punched by a forlorn-looking unicorn's horn).

The entire enterprise is housed in a dreary-looking factory sprawl surrounded by barbed wire and identified by the looming 20th Century Fox logo and searchlights.

Through its long history, The Simpsons has never hesitated to lampoon its network bosses and other Fox programming.

But Sunday's self-inflicted jab was inspired by the fact that much of the rote production work for each Simpsons episode is indeed outsourced from the series' L.A. creative hub to studios in South Korea.

The sequence's mastermind, Banksy, is an international figure in street art who is known for traveling the world and anonymously leaving his signature pieces in public areas while refusing to reveal his real name.

On Monday, Simpsons executive producer Al Jean said he had hit on the idea of inviting Banksy to create a so-called "couch gag" after seeing the film he directed, Exit Through the Gift Shop, which was released earlier this year.

The Simpsons casting director managed to track down the famously hard-to-reach artist, and a few months later his work was submitted.

Although Jean said the segment was "toned down a little" for airing, "there was nothing unusual from the network in terms of notes or delays.

"Fox has a remarkable ability to make fun of itself and be gracious," he said.