The 29-year-old socialite met 16-year-old popstar Justin Bieber at the White House Correspondents' Dinner on Saturday, where the two reportedly got on well.
After posting a photo of the pair together on TweetPhoto, the 'Baby' singer tweeted: "Look its my girlfriend @kimkardashian."
In reply, Kardashian retweeted the post, adding: "I officially have Bieber Fever!!!"
Earlier this week, when asked about Kardashian, Bieber told Showbiz Spy: "I think she's cute. And, no, she's not too old for me."
He has also said that he would like to date Meagan Good and Beyoncé, and has been said to have developed a crush on comic Tina Fey.
Both Kardashian and Bieber are currently single.
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