Mariah Carey has admitted that she is dissatisfied with her performance at the Michael Jackson public memorial service held at Staples Center on July 7 in Los Angeles.

She stated on the social network site Twitter that the moment was too emotional for her to be at her best, the New York Daily News reports.

She said: "Trying to sing today was basically impossible for me, I could barely keep myself from crying.

"I'm sorry that I wasn't able to pull it together and really do it right, but I was literally choked up when I saw him there in front of me."

The singer further wrote: "One thing I know is, we will never really have to say goodbye to MJ. His legacy lives on through his music and the millions of people he inspired with his timeless music. He will be forever in our hearts."

Carey had performed cover of The Jackson 5 hit, "I’ll Be There," with Trey Lorenz.