Peter, 37, called his lawyers after he discovered a burn under three-year-old Princess’s armpit, but Amy insists Katie is not to blame as she was looking after the tot herself at the time.
She told the Daily Mirror: “I don’t understand why Pete is having a go at Kate.
“Her sister Sophie and I were the ones with Princess when it happened and I know it was a fluke accident – and just how minor it is.”
Princess burnt herself leaning against a heated towel rail when the Price family were on holiday at ski resort Klosters.
Amy continued: “Princess went straight back to playing. She slept soundly without pain and a week later there was barely a mark on her.”
Katie wrote “Love my mum” on her Twitter account this morning in support of Amy’s comments.
The glamour girl posted a statement on her website accusing Peter of “using the incident to portray me as a bad mother while providing footage for his TV show.”
However, Peter and his management deny they were responsible for the story making its way in to the press.
The ex-couple are preparing for a showdown tonight at the Brit Awards.
Peter will be carrying out red carpet interviews at the ceremony, and Katie has managed to bag herself an invite.
Last night she tweeted pictures of her manicure to fans, saying: “Off to brits tomorrow which nail polish pricey drama” (sic).
When a follower tweeted that Peter must be jealous at her also getting an invite, Katie replied: “I agree.”