Alexandra Burke was left terrified when a restaurant diner threatened to stab her to death.

The 'Elephant' singer was enjoying a meal with her mother Melissa Bell and brother Nick when they saw a tweet from a fellow patron claiming Alexandra was so annoying that he wanted to attack her.

Melissa told Nick Ferrari's LBC 97.3 radio show: "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.'"

The family then checked the twitter user's profile picture so they could find him in the eatery and Nick, a protection officer, "lost it" and confronted the man.

Melissa added: "My son absolutely lost it. He was very sheepish and said, 'I'm so sorry, it was a joke'. But I was very scared. We said, 'How dare you? This is threatening someone's life.'"

Alexandra, 23, recently revealed she was surprised when former 'X Factor' mentor Cheryl Cole reached out to her on twitter after previously ignoring her text messages.

On March 3, Cole wrote: "Omg !!.. Where have I been .. Alexandra looking HOT !! In her new Video.. #YesAlex .. Ps.. Text me your secrets please lmao (sic)."

Alexandra said: "I haven't heard anything from Cheryl for over a year and then she tweeted me publicly the other day, which I was really surprised about. I've texted her a few times but never heard anything back.

"I was surprised to hear from her on twitter, which was very public. Don't get me wrong, it was great for her to get in touch and it was a very lovely message, but I would prefer to hear from her more privately and maybe go for a drink and catch up properly."