The British star feels increasingly vulnerable when making public appearances and has stopped being as accessible to her admirers.
Speaking at the signing of her new novel Paradise at a HMV store in London on Wednesday, she said: "I always used to do pictures for fans in front of the signing table but I don't do that any more. I have changed everything. I feel safer sitting behind the table now.
"It ruins it because it now means you can't do pictures with the fans. But you never know if they've got a knife or something. I don't want to get hurt. I've got the best security, I just have to be more careful these days."
In the past two weeks, Katie was booed by the crowd when she performed her single Free To Love Again at a nightclub in Southend, Essex, and was also jeered when she accompanied husband Alex Reid to a cage fight in Portsmouth.
Katie fears she could suffer the same fate as Bleeding Love singer Leona Lewis, who was attacked by a fan last year while promoting her autobiography Dreams.
The 32-year-old star - whose ex-husband is Peter Andre - said: "It's a shame when something like the Leona Lewis incident happens."
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