As we previously reported, Queen B has been accused of miming along to national anthem The Star-Spangled Banner, with the Marine Corp Band previously stating Bey decided before her stint on the podium to use the studio-recorded version rather than sing live.
Keys has now defended the former Destiny's Child singer, telling Capital FM that Beyoncé is an "incredible" artist and that there is "not doubt" she can sing live.
The Girl On Fire singer - who also performed at Obama's inauguration celebrations - told the radio station: "What I do know is that Beyoncé is a great performer and she's an incredible artist with a really, really powerful voice.
"The one thing that you cannot doubt is that she can sing. She absolutely can sing. All the rest of the 'whys' or 'whatever', we know that she can deliver and she did deliver that song really beautifully."
Bey herself is yet comment on the allegations, with Aretha Franklin - who sang the national anthem at Obama's 2009 inauguration - telling ABC News: "I thought it was funny because the weather down there was about 46 or 44 degrees and for most singers that is just not good singing weather.
"When I heard that I just really cracked up. I thought it was really funny, but she did a beautiful job with the pre-record."
Entertainment Weekly have since reported that The Marine Corp Band have released a statement confirming they DID perform to a pre-recorded track.
They claimed: "The Presidential Inaugural Committee (PIC) requested that the Marine Band accompany Beyoncé Knowles-Carter in the performance of 'The Star-Spangled Banner' at the 2013 Inaugural Ceremony," the statement reads.
"However, there was no opportunity for Ms Knowles-Carter to rehearse with the Marine Band before the Inauguration, so it was determined that a live performance by the band was ill-advised for such a high-profile event."
They added: "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.
"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."
An official has since alleged to CNN that Bey decided to mime due to her lack of rehearsal time, telling the news organisation: "She did not sing live because she didn't have time to rehearse with the Marine Band [on Sunday], she decided to use her recording [for the performance] with the Marine Band."
The official added that her pre-recording of the track "was spot on", adding: "She's actually a very good live singer."
Watch MTV News on the hour every hour on MTV - Sky Channel 126 and Virgin Channel 134