Beyonce sings the national anthem during the inauguration ceremonies for United States President Barack Obama in Washington.

London - Beyonce Knowles reportedly lip-synced the American national anthem at Barack Obama's inauguration on Monday.

The Halo hitmaker - dressed in a demure black dress with emerald earrings - sang The Star Spangled Banner in Washington DC immediately following the president's swearing-in and speech but the audio is said to have been pre-recorded amid reports she only had one night to rehearse with the band before the performance.

A spokesperson for the Marine Corps Band told the The Times newspaper in London: “We don't know why Beyonce decided to use pre-recorded music. All music (for inaugural ceremonies) is pre-recorded as a matter of course, and that's something we've done for years and years. The Marine Band did perform live throughout the ceremony but we received last-minute word that Beyonce wanted to use the recording.”

The representative also told gossip website “We all know Beyonce can sing... We don't know why she chose to use the pre-recorded track.”

A source told Buzzfeed before the inauguration that the singer only had one night to rehearse with the band as she is currently preparing for her high-profile show at the Super Bowl in New Orleans on February 3, during which she will be joined by her Destiny's Child bandmates Kelly Rowland and Michelle Williams.

The band's director Colonel Michael J. Colburn said: “As soon as we get information from the Presidential Inaugural Committee about who the guest artists are going to be, we make contact with them, find out how we can prepare arrangements that will really kind of flatter their voices - of course in the right key.

“We had Kelly Clarkson in over the weekend to rehearse and record. Beyonce, she's getting ready for the Super Bowl, so we didn't have a chance to do anything with her until last night.

“It's a very, very tight window of opportunity.”

Other performers at the event - including newly-engaged Stronger singer Kelly - sang live. - Bang Showbiz