Beyonce sings the National Anthem during inauguration ceremonies for US President Barack Obama in Washington, January 21, 2013. [Photo/Agencies]

Never mind President Barack Obama's inauguration address or what Michelle Obama was wearing at the ball.

Was Beyonce lip-synching the US national anthem on Monday, or wasn't she?

The Grammy-winning singer remained silent on Tuesday amid a media storm over whether she was lip-synching, singing over her own pre-recorded track, or performing live when she delivered a flawless version of "The Star-Spangled Banner" to hundreds of thousands of people in Washington and millions watching on television.

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A spokeswoman for the US Marine band first told US news outlets on Tuesday that the "Single Ladies" star "decided to go with the pre-recorded music at the last minute" and that, to the spokeswoman's knowledge, she was not actually singing the anthem.

But the US Marine band later backtracked, saying in a statement: "Regarding Ms. Knowles-Carter's vocal performance, no one in the Marine Band is in a position to assess whether it was live or pre-recorded."

The statement said the band and Beyonce, whose surname is Knowles-Carter, had no chance to rehearse together before Monday's inauguration "so it was determined that a live performance by the band was ill-advised for such a high-profile event.

"Each piece of music scheduled for performance in the Inauguration is pre-recorded for use in case of freezing temperatures, equipment failure, or extenuating circumstances," the Marine Band added.

Beyonce, 31, was giving her first major public performance since giving birth to a baby with husband, rapper Jay-Z, in January 2012. On Sunday, she posted on Instagram photo of herself in a recording studio holding the sheet music for "The Star-Spangled Banner".