The chief federal regulator of broadcasting said Monday he is outraged by the Super Bowl (search) halftime show which wound up with singer Justin Timberlake (search) tearing off part of Janet Jackson's (search) costume, exposing her breast.

Timberlake blamed a "wardrobe malfunction," but Federal Communications Commission chief Michael Powell called it "a classless, crass and deplorable stunt."

MTV, which produced the show, and CBS, which broadcast it, both said they had no idea that their halftime show Sunday night would include such a display.

"CBS deeply regrets the incident," spokeswoman LeslieAnne Wade said.

The two singers were performing a flirtatious duet to end the halftime show, with Timberlake singing, "Rock Your Body," and the lines he sang at the moment of truth were: "I'm gonna have you naked by the end of this song."

With that, Timberlake reached across Jackson's leather gladiator outfit and pulled off the covering to her right breast, which was partially obscured by a sun-shaped, metal nipple decoration.

The network quickly cut away from the shot, and did not mention the exposure on the air.

In a statement, Powell said, "I am outraged at what I saw during the halftime show of the Super Bowl. 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."

"I have instructed the commission to open an immediate investigation into last night's broadcast," he said, vowing it would be "thorough and swift." Earlier, an FCC spokeswoman, Suzanne Tetreault, said it was launching a routine investigation because it had received complaints.

Messages left with Jackson's record company and her personal publicist were not returned Monday morning.

MTV, CBS' corporate cousin in Viacom, issued a contrite statement in which it also apologized, saying the incident was "unrehearsed, unplanned, completely unintentional and was inconsistent with assurances we had about the content of the performance."

Timberlake said he did not intend to expose Jackson's breast.

"I am sorry that anyone was offended by the wardrobe malfunction during the halftime performance of the Super Bowl," Timberlake said in a statement. "It was not intentional and is regrettable."

Wade said CBS officials attended rehearsals of the show all week, "and there was no indication any such thing would happen. The moment did not conform to CBS' broadcast standards and we would like to apologize to anyone who was offended."

The show also featured P. Diddy (search), Nelly (search) and Kid Rock (search).

"We were extremely disappointed by elements of the MTV-produced halftime show," Joe Browne, NFL executive vice president, said. "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 halftime."

Over-the-air television channels cannot air "obscene" material at any time and cannot air "indecent" material between 6 a.m. and 10 p.m. The FCC defines obscene material as describing sexual conduct "in a patently offensive way" and lacking "serious literary, artistic, political or scientific value." Indecent material is not as offensive but still contains references to sex or excretions.