Pop icon Michael Jackson has died after suffering a cardiac arrest, multiple US media outlets report, sending shockwaves through the entertainment world.

The Los Angeles Times and TMZ.com celebrity news website reported Jackson, 50, died after suffering an arrest just after 12pm local time (0500 AEST) and paramedics were unable to revive him.

The Times cited multiple city and law enforcement officials as confirming the pop icon's death.

Jackson's manager Tohme E. Tohme was not available for comment. Officials at UCLA Medical Centre where Jackson was treated also could not be reached for comment.

National and local television networks showed hundreds of media gathered at UCLA Medical Centre for what appeared to be a briefing.

Los Angeles Fire Department spokesman Devin Gales did not confirm Jackson's identity but said paramedics went to an address corresponding to the star's home at 12:21pm (0521 GMT) and the person was taken to UCLA Medical Centre.

An unidentified family member earlier told TMZ -- the first outlet to report that Jackson had suffered a cardiac arrest -- that the star was in 'really bad shape.'

Michael's father Joe Jackson told E! Online he was aware of the emergency but did not know further details.

'I am in Las Vegas, but yes, people in Los Angeles called me and are with Michael and tell me he was taken to the hospital,' he said.

'I am not sure what's wrong. I am waiting to hear back from them.'

The reports came as Jackson prepared to make a keenly anticipated concert comeback in London, his first series of shows in more than a decade and the first since his 2005 acquittal on child molestation charges.

However those concerts -- billed as the 'final curtain' -- had been thrown into doubt after Jackson pushed back the opening dates last month.

Organisers of the concerts at the time stressed the delay was not linked to Jackson's health.

In a press conference from the United States broadcast over the internet, AEG Live president Randy Phillips was asked about Jackson's health and said: 'I would trade my body for his tomorrow. He's in fantastic shape.'

While Jackson reigned as the King of Pop in the 1980s, his once-stellar career had been overshadowed by his colourful public behaviour, his startling physical transformation and multiple allegations of child abuse.

Jackson lived as a virtual recluse following his 2005 acquittal on charges including child molestation and plotting to kidnap his young accuser.

Despite his acquittal, the trial was a body blow from which the pop music superstar struggled to recover.

Four years later, Jackson is still worshipped by fans for revolutionising music, dance and music videos at the peak of his success.

The attention however paid to him in recent years has been less flattering, focusing on apparent cosmetic surgery -- which he denies -- his baby dangling antics and a decade of swirling child abuse allegations.

Born on August 29, 1958, Jackson made his show business debut with four of his older brothers in the Jackson Five pop group, and went on to lead the stage clan with a piping soprano and dazzling dance moves.

By 1969, the group had signed a contract with Motown Records, becoming one of the last great acts to emerge from the legendary label.

The Jacksons produced seven platinum singles for Motown, selling over a million, and three multi-platinum albums, selling more than two million.

They moved to CBS's Epic Records in 1976.

Despite the early success, Jackson was to recall those years as unhappy and lonely ones. Eventually the family act broke up, as Jackson went solo.

In 1979, Quincy Jones produced Jackson's first solo album for Epic, Off the Wall, a huge disco-oriented success that sold 10 million copies.

They teamed up again in 1982 for what would be Jackson's breakthrough album as a composer and co-producer, Thriller, which became the top-selling album of all time, with sales exceeding 41 million.