Gossip Girl star Leighton Meester and actor Sebastian Stan are engaged after reportedly announcing their marriage plans on social networking site Facebook.com.

Meester, 23, has been dating 25-year-old Stan since he appeared on her hit TV show last year - and now they are ready to make their romance official by exchanging vows.

The New York Post's gossip column Page Six claims the stars both changed their relationship status to "engaged" on their online profiles this week and Meester's representative has fuelled the reports by refusing to comment.

The news comes just days after a sex tape purportedly starring the actress sparked a bidding war between online porn sites, with offers for the video exceeding $1 million. The racy footage allegedly features a younger Meester performing a striptease for a former boyfriend as well as a number of sensual and erotic acts.

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(This news article provided by World Entertainment News Network)