Beyonce Knowles is said to be bitterly disappointed by reaction to her performance of the American national anthem at Barack Obama's inauguration on Monday (21.01.13).

The 'Halo' hitmaker - who allegedly mimed 'The Star Spangled Banner' in Washington DC immediately following the president's swearing-in and speech because she only had one night to rehearse with the US Marine Corp Band before the performance - reportedly feels she did nothing wrong and the controversy has tarnished what was supposed to be a momentous occasion.

A source close to the 'Diva' singer said she is very disappointed, saying she feels ''a technicality which everybody does took away from the beauty of the moment.''

The source also confirmed to USMagazine.com that the 31-year-old singer used a backing track, but explained that this is completely normal for an outdoor performance and insisted she also sang parts of the song live.

The insider said: ''She didn't think there was anything wrong with it. Pavarotti has done it! It was freezing out, and if she messed up just one note, that would have been the story.

''Everybody uses these tracks, and the music director advised it. Any big outdoor live performance is almost always with some kind of track.

''She did sing, but used a track.''

A spokesperson for the Marine Corps Band was the first to reveal that Beyonce did not sing live and previously explained: ''We don't know why Beyoncé 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 Beyoncé wanted to use the recording.''