Michael Jackson returned to the stage at a star-studded World Music Awards in London last night, but only managed to sing a few lines of his hit "We Are The World." Jackson was at the event to collect a Diamond Award for selling more than 100 million albums. But what was billed as a spectacular comeback for the world's biggest star fell flat. Fans outside the Earls Court venue were left fuming when Jackson failed to greet them and then revealed he wouldn't be performing - despite reports he would sing live in the British capital for the first time in nine years. Inside, the arena was only half full. The superstar did make it onstage to join a gospel choir performance of the 1985 song he co-wrote with Lionel Richie - but he barely uttered a line. Jackson was presented the Diamond Award by Beyonce Knowles and also a Guinness World Record for Thriller, the biggest selling album of all time. During an emotional speech, Jackson thanked his friends, family and fans. He said, "I'm greatly humbled by this award. It was my dream that thriller would become the biggest selling album ever. I thank God and you for it's success. There have been so many who have loved and stood by me for the 25 years I have been in the entertainment industry. I'd like to thank my children particularly. Paris, Prince Michael and Blanket (Prince Michael II) for their unconditional love. I love all my fans from the bottom of my heart."