Michael Jackson's three children have joined thousands of the late pop star's fans for a memorial concert at Cardiff's Millennium Stadium. Prince Michael, 14, Paris, 13, and Prince Michael II, nine, watched acts including Christina Aguilera, Smokey Robinson, Leona Lewis and boy band JLS. They took to the stage dressed in outfits reflecting Jackson's career and were greeted by rapturous applause. The Michael Forever gig honoured the star who died in 2009, aged 50. Jackson's three children introduced Beyonce's performance, with his youngest looking stunned by the noise and lights, but the elder two seeming at ease on stage. Paris told the audience: "We're very happy to be here on this special night to honour our father." Beyonce, who wore her hair in a Jackson Five-style afro, played one of the group's hits, Where You Are, saying it was the first song she had performed with her former group Destiny's Child. Michael Jackson's brothers, Tito, Marlon and Jackie, performed at the event, which was hosted by actor Jamie Foxx and presenter Fearne Cotton. Michael Jackson's sister, La Toya, came out of retirement to perform. "I have put musical performance behind me for roughly two decades," she said. "But there will never be another magical moment such as this to celebrate Michael with his fans to perpetuate the importance of his legacy. "I am honoured to share the stage with the incredible performers in this line-up, and I'm certain nothing would make my brother smile bigger or brighter than this tribute concert." However, not all the Jackson family were behind the concert. Two other siblings, Jermaine and Randy Jackson, said the concert was "inappropriate" and "ill-timed" because it was held during the criminal trial of Conrad Murray, the doctor charged with involuntary manslaughter over the star's death in June 2009. Jackson's sister Janet Jackson also decided not to attend. Marlon Jackson said he respected their decision and added: "Each one of us grieves differently. We want to celebrate the positive side of his life, the positive things that he did." 'Celebrating the music' R&B star Ne-Yo, who gave a rendition of Billie Jean, said: "It's not about the controversy. It's not about the trial. It's not about his death. It's about celebrating his life. It's about celebrating his music." Michael Jackson fan Helen Rees-Smith, from Blackwood, in Caerphilly county, was at the concert. "It's a chance to remember what a great talent he was and to show his family that the memory lives on," she said. Paul King, one of the organisers, said there had been a slow start to ticket sales, but added: "All of a sudden this week it exploded and we were selling 1,000 tickets an hour yesterday." The show was expected to have sold out. Chart-toppers Black Eyed Peas withdrew from the line-up of the Michael Forever concert last week. Mr King told BBC Radio Wales that losing the group from the bill had allowed the show to be "tightened up", and extra songs allocated to some of the "major artists" involved.