According to a weekend tabloid report, Holden was concerned former Strictly Come Dancing star Dixon didn't like her after snubbing her birthday invitation.
Ex-Wild at Heart actress Holden was said to feel frozen out by producers after the introduction of Dixon.
However, Dixon told the BGT website: "I love Amanda. There were reports over the weekend saying that there is rivalry between us, alongside claims that we're not getting on.
"This is absolute rubbish and totally untrue. We're really close friends and I think she's great."
The singer added: "It's always unfair when the press try to pit women against each other. Where's the sisterhood in that?"
> Britain's Got Talent Amanda Holden, Alesha Dixon: 'We won't be at war'
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Watch Digital Spy talk to Amanda Holden and Alesha Dixon at the BGT launch below: