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Photos have surfaced of Selena Gomez, 18, cuddled up to Justin Bieber, 16, in the Caribbean, and some of the "Beliebers" have taken to their Twitter to show they are not thrilled with the idea of the teen heartthrob being in a relationship.

One Bieber fan tweeted: "@SelenaGomez, [I] swore [to] my mom that if you broke [his] heart revenge will be great, I promise ... and I'm not alone in this ... be careful."

Another tweet read: "Dear @SelenaGomez , We all know [you're] dating Justin Bieber :] So get out of your cage and stop acting innocent!"

One fan wasn't crazy about the age difference between the teen stars, tweeting in part: "[You're] 18, he's 16. Find a man your own age."

This isn't the first time Bieber fans have gone after one of the pop star's female friends. Kim Kardashian said she received death threats via Twitter after Bieber posted a picture of them together at the White House Correspondents dinner in May 2010.

However, there are some supporters of the rumored romance between Gomez and Bieber. Tweets have been circulating that read: "stop hating" and "@selenagomez, I just love you and I will support you no matter who you date or what you do."

Related on Wonderwall & MSN:

What happened to Selena's purity ring?

Learn all about Bieber's music career

Find out how Bieber was a fashion hit in 2010

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