Rihanna on red alert

RIHANNA is reportedly stepping up her personal security after receiving X-rated letters from a crazed fan.

RIHANNA is reportedly stepping up her personal security after receiving X-rated letters from a crazed fan.

The Rude Boy singer is said to be shocked by the graphic fan mail and her boyfriend, baseball player Matt Kemp, is believed to have made sure the obsessed letter writer, who calls himself 'Buster', can't get to her.

A source told Daily Star: "Matt has asked her team to be extra cautious after she received two steamy letters.

"Her friends are also concerned that things with this guy are going to get out of hand."

In what could be a result of her new security measures, the 22-year-old singer reportedly had a gold golf cart when she appeared at the Nickelodeon's Kids' Choice Awards in Los Angeles on Saturday, which took her just 17 metres from one side of the backstage area to the other.

Rihanna also performed at the ceremony, playing three songs, Hard, Rude Boy and Don't Stop the Music.

Speaking at the awards ceremony, Rihanna said she intends to develop her sound on her next record.

She told MTV: "Rated R, I love the sound of it, in terms of the bass. I really like the bottom, the grime of it. But if I were to combine that with more energetic, up-tempo pop records, then I think that will be a happy marriage. And that's where we'll probably go next." - Bang

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