(CNN) -- Ahead of her Super Bowl halftime show, singer Madonna promised there would be no "wardrobe malfunction." What she didn't guarantee was no obscene gestures.
Rapper M.I.A. provided a middle finger salute to network cameras Sunday night during the 12-minute extravaganza, when she joined Madonna during a performance of the latter's new single, "Give Me All Your Luvin'."
The apologies from the NFL and the broadcaster, NBC, came quickly -- they blamed each other.
"There was a failure in NBC's delay system," said Brian McCarty, the league's vice president of communications. "The obscene gesture in the performance was completely inappropriate, very disappointing, and we apologize to our fans."
"The NFL hired the talent and produced the halftime show," NBC said. "Our system was late to obscure the inappropriate gesture and we apologize to our viewers."
The episode was reminiscent of the 2004 Super Bowl when singer Janet Jackson's nipple was briefly exposed during a performance with singer Justin Timberlake.
The infamous "wardrobe malfunction" episode, as it came to be known, prompted the Federal Communications Commission to fine broadcaster CBS $550,000. In November, a divided 3rd Circuit Court of Appeals ruled the FCC improperly punished the network.
Since then, the NFL has maintained tight control over the show's production.
After the Jackson-Timberlake showstopper, the halftime show largely relied on classic rock artists such as Paul McCartney, Bruce Springsteen, The Rolling Stones, The Who and Tom Petty.
Fast forward to Sunday when the New England Patriots were again playing in the big game, just as in 2004.
M.I.A., along with Nicki Minaj, Cee-Lo Green and LMFAO, joined Madonna as she treated fans to a greatest hits medley that included "Vogue," "Music" and "Like a Prayer."
The "spontaneous gesture," as NBC called it, came during a performance of Madonna's latest single. M.I.A. not only flipped her middle finger but uttered, "I don't give a sh*t."
A source close to M.I.A. said the rapper "was nervous and not thinking, and adrenaline took over."
"It wasn't meant as a gesture or statement of any kind," said the source, who is not authorized to speak on the record. "She feels horrible for putting Madonna in that position. She messed up."
The Parents Television Council, a nonprofit group that advocates for family friendly programming, blamed the mishap on both NBC and the NFL.
"They chose a lineup full of performers who have based their careers on shock, profanity and titillation," the group's president, Tim Winter, said in a statement. "Instead of preventing indecent material, they enabled it."
Madonna did not issue a comment. But on Twitter, where the halftime show generated 8,000 tweets per second, the reaction was swift and mixed.
"What was that singer M.I.A. thinking?! Flipping off America during halftime can't be a good career move," Will Ripley of Denver tweeted.
But Devon Soltendieck of Montreal was less concerned.
"Can we all stop pretending #MIA flipping the Finger during the halftime show is offensive in 2012?" he asked.
Said Josh Jackson, editor in chief of the music magazine Paste: "M.I.A. Didn't flip us all off. She just had a middle finger malfunction."
CNN's K.J. Matthews contributed to this report