Justin Timberlake and Janet Jackson were today accused of a “classless, crass and deplorable” Super Bowl show stunt during which she exposed one of her breasts.
The condemnation came from the United States’ top broadcasting regulator, which ordered an immediate investigation.
The pop stars denied the stunt was deliberate and Timberlake blamed a “wardrobe malfunction”.
The pair’s half-time show sparked thousands of complaints, when Timberlake tore away part of her top covering her right breast.
An estimated 130 million people in the US were watching the Super Bowl. As he tugged at her top Timberlake sang: “I’m gonna have you naked by the end of this song.”
TV network CBS said it “deeply regretted” the incident.
A spokeswoman said executives had watched rehearsals during the week “and there was no indication any such thing would happen”.
She said: “The moment did not conform to CBS’s broadcast standards and we would like to apologise to anyone who was offended.”
Federal Communications Commission chief Michael Powell said he was “outraged” at the display.
“Like millions of Americans, my family and I gathered around the television for a celebration.
“Instead, that celebration was tainted by a classless, crass and deplorable stunt. Our nation’s children, parents and citizens deserve better.”
He went on: “I have instructed the commission to open an immediate investigation into last night’s broadcast.” He added that it would be “thorough and swift”.
Timberlake said he did not intend to expose Jackson’s breast.
“I am sorry that anyone was offended by the wardrobe malfunction during the half-time performance of the Super Bowl,” he said in a statement. “It was not intentional and is regrettable.”
Joe Browne, the executive vice-president of the sport’s governing body, the NFL, said: “We were extremely disappointed by elements of the MTV-produced half-time show.
“They were totally inconsistent with assurances our office was given about the content of the show.
“It’s unlikely that MTV will produce another Super Bowl half-time.”
MTV issued a statement saying the incident was “unrehearsed, unplanned and, completely unintentional”.
But many questioned whether the incident was in fact planned.
Jackson was wearing an ornamental star-shaped decoration on her breast, and some news commentators pointed out that her top appeared to come away too easily.
“Shocking as it was, it was not a mistake. It’s really sad. How are we going to up the ante next?” asked Barbara Lippert, advertising critic at trade report AdWeek.
The stunt follows a number of raunchy scenes during large-audience shows.
In August Britney Spears and Madonna attracted global headlines with an on-stage kiss during the MTV Music Video Awards.
Timberlake also made the front pages for groping Kylie Minogue’s bottom during a stage performance.
Jackson’s record company and publicist were not available for comment.
The half-time show also featured P Diddy, Nelly and Kid Rock.