Beyoncé Knowles lip-synched America's national anthem at President Barack Obama's inauguration.

Monday''s Washington, DC ceremony marked the start of Obama's second term as President of the United States.

Millions tuned in to watch the television broadcast as the president was sworn into office and singers including Beyoncé, Kelly Clarkson and Jennifer Hudson lined up to perform.

Beyoncé stepped onto the podium to sing The Star-Spangled Banner to a cheering crowd.

A spokesperson for the Marine Corps Band that accompanied her performance told TMZ the 31-year-old diva was not singing live.

The website reported it is standard procedure to record a backing track for a live performance such as Beyoncé's and she 'decided at the last minute to rely on the studio version instead of winging it in person".

'We all know Beyoncé can sing... We don''t know why she chose to use the pre-recorded track,' the spokesperson added.

The Marine Corps Band representative noted Kelly Clarkson's rendition of My Country, ''Tis of Thee was performed live.

Jennifer Hudson meanwhile had the honour of performing as President Obama and First Lady Michelle Obama shared their first dance.

It was unknown at press time if Jennifer''s performance of Al Green's Let's Stay Together was pre-recorded.