Beyonce Knowles sang with a pre-recorded track at President Obama's inauguration because she didn't have enough time to rehearse.

Speaking at a press conference on Thursday (31.01.13), which she opened by singing the national anthem for assembled journalists, Beyonce said: “I am a perfectionist, I will practise until my feet bleed but I didn't get a chance..

“The inauguration was about the president I wanted to make him and the country proud. I decided to sing along with my pre-recorded track which is something that is common in the music industry. I always sing live, the inauguration was unfortunately a time when I didn't have time to rehearse with the the orchestra because I was rehearsing for the Super Bowl. I'm very proud of my performance.”

Speaking about the Super Bowl, she added: “I will absolutely be singing live, I am well rehearsed. This is what I am born for.

“I've had a 16 year career and everything I've done has prepared me for this, I'm ready. It is something we've been preparing for for about four or five months but I am nervous.”

While it has been speculated Beyonce will be joined on stage at the half-time show by her Destiny's Child bandmates Kelly Rowland and Michelle Williams, the singer refused to give away any details.

She said: “I can't give away any details but I will say there is nothing like our connection and the sisterhood we have, it's always a pleasure to be around them personally and professionally.”

Beyonce, 31, also revealed she can't wait until her performance is over so that she can spend time with her husband Jay-Z and their 12-month-old daughter Blue Ivy.

She explained: “I can't wait until it's all over, I'm gonna enjoy my daughter. I miss her so much and I keep saying 'mommy is so busy but I'll be done at 9pm on Sunday.'”

The busy singer's HBO documentary 'Life Is But A Dream' will air on February 16 and while she is nervous about sharing her ups and downs with everyone, Beyonce wanted to make the movie for Blue Ivy's sake.

She said: “I'm very nervous about reaction to my documentary. It was interesting seeing the mistakes I've made and putting them in the documentary. It's time for people to see me and see a different side to me and I'm scared but I'm happy.

“My daughter has changed me and changed my life and given me so much purpose. This movie is necessary and shows a human side. My job is to protect her and I am happy to tell my life story on my own terms.”