Speaking on Nick Ferrari's LBC 97.3 show, Bell said: "We were in the restaurant and looked at Twitter to see my daughter's status and someone had written; 'I'm in a restaurant with Alexandra Burke. She's annoying me and I'm going to go over with my steak knife and stab her to death'."
Explaining that they had used the Twitter user's profile picture to identify him, the former Soul II Soul singer said that her son David, a protection offer and strong supporter of his sister's career, "lost it" when he confronted the sender.
"He was very sheepish and said; 'I'm so sorry, it was a joke'," Bell said. "But I was very scared. We said, 'How dare you?' This is someone threatening someone's life."
Writing on her own Twitter account recently, Burke said: "If you haven't got nothing nice2 say. Just don't say anything at all... Some people need to grow up before I let it RIP on them. Having hate in your heart for someone you don't know is so wrong... #DontJudgePeopleUntilUKnowThem! (sic)"