A letter containing suspicious white powder that was sent to reality TV star Khloe Kardashian sparked a studio security scare on Tuesday morning (20Nov12).

FBI agents launched an investigation after producers alerted them to the discovery of an envelope mailed to CBS studios, where the fashion designer tapes her hosting gig on The X Factor.

The officials determined the substance was harmless, reports TMZ.com.

This is the third time a mysterious powder has been delivered to the production facility - former Dancing With the Stars contestant Bristol Palin was also twice targeted.