MOSCOW, June 26 (RIA Novosti) - Michael Jackson, the U.S. pop star whose career spanned five decades, has died of a heart attack in Los Angeles. He was 50.

Emergency services were called to his Beverly Hills home at 12.21 p.m. on Thursday (19.21 GMT), the TMZ.com website said. He was pronounced dead some three hours later at the UCLA medical centre.

His death came shortly before he was about to take part in series of comeback concerts in London.

His brother, Jermaine, told journalists that doctors had attempted to revive the singer for more than an hour.

"The family request that the media please respect our privacy during this tough time," he added.

Jackson, born in Gary, Indiana, near Chicago spent almost his entire life in the public eye, shooting to stardom in the 1970s with the Jackson 5, a pre-teen Michael and brothers stunning the U.S. with their vocals and synchronized dance routines. The group, who recorded for Motown, was the first to see their four debut singles reach the top of the U.S. charts.

As an adult, his Thriller album sold more than 50 million copies worldwide, making it the best selling album of all time.

His later career was hit by allegations of child abuse and financial difficulties.

"Today, the world has lost one of the most influential and iconic figures in the music industry. From his performances with the Jackson 5, to the premiere of the 'moonwalk' and 'Thriller,' Michael was a pop phenomenon who never stopped pushing the envelope of creativity," California Governor Arnold Schwarzenegger said in a statement.