LONDON: Rumours are abuzz that Natalie Portman is romancing a co-worker, just weeks after her rep denied she is dating Australian actor Chris Hemsworth.

A spokesperson for Portman, 28, dismissed reports last month (December 2009) after online gossips suggested she was dating the Star Trek actor.

But now, gossip mills have gone into overdrive with reports that the actress is reportedly involved with 32-year-old Benjamin Millepied, who worked as a choreographer on her new ballet movie, Black Swan.

Portman reportedly showed off her new boyfriend at a New Year's Eve party in New York City.

"She has been subletting Sarah Michelle Gellar's apartment and she wanted to celebrate the New Year with a few close friends and introduce them to Ben. They have actually been a couple since the fall, but she wanted to see how serious it was before she started to show him off to her inner circle. She really likes him,” the Daily Express quoted a source as telling In Touchmagazine.