Jackson was exposed during a routine with Justin Timberlake

TV network CBS, which broadcasts the Grammys and the Super Bowl, will extend its usual time delay to give them more time to edit out unexpected slip-ups.

Jackson has issued another apology after her right breast was exposed during a half-time performance.

She said she changed her routine with Justin Timberlake at the last minute.

"My decision to change the Super Bowl performance was actually made after the final rehearsal," she said.

CBS, MTV - which produced the performance - and the National Football League "had no knowledge of this whatsoever", she said.

HAVE YOUR SAY There was more naked flesh on show in the Super bowl adverts than in Ms Jackson's performance. Where is the outcry about that? Timothy, UK Send us your comments

"Unfortunately the whole thing went wrong in the end. I am really sorry if I offended anyone. That was truly not my intention."

The mistake has caused outrage in some quarters in the US, with Federal Communications Commission (FCC) chairman Michael Powell saying it was a "classless, crass and deplorable stunt".

The FCC, the main government media watchdog, has announced an inquiry to see whether the display of flesh constituted indecency.

Timberlake is due to perform at Sunday's Grammy Awards, while Jackson has been lined up to present an award.

Why was the US so enraged by Janet Jackson's exposure?

CBS is now trying to adapt video systems to allow them to delay the live broadcast for longer than the usual five seconds.

Standards

The network's executive vice-president Martin Franks said: "Unfortunately, we cannot count on those who appear on our air to live up to our standards."

The five-second delay has previously been used to bleep out swearwords, such as when Eminem performed at the ceremony in 2002.

Prince, Beyonce Knowles and rapper 50 Cent are among the other stars lined up to perform at the ceremony at the Staples Center in Los Angeles.