Meester dating 'Gossip Girl' co-star?

Leighton Meester is rumoured to be dating Gossip Girl co-star Sebastian Stan.

The actress, who plays Blair Waldorf in the US teen drama, was spotted kissing Stan (Carter Baizen) at a dinner to mark Nylon magazine's Young Hollywood issue in New York.

A source told PageSix: "[They] couldn't keep their hands off of each other... they didn't care."

Blake Lively (Serena van der Woodsen) was also spotted cosying up to Penn Badgley (Dan Humphrey) at the event.

Meester recently denied that she is romantically involved with fellow co-star Chace Crawford (Nate Archibald).