Bradley Cooper and his girlfriend Zoe Saldana kissed for 20 minutes to celebrate the start of 2012.

The Hollywood heartthrob and the sexy actress attended a private 1940s-themed party on New Year's Eve (31.12.11) at a Bel Air property in Los Angeles

When the clock struck midnight, the lovebirds embraced each other for a lengthy smooch.

A source told "They were making out for 20 minutes!"

Bradley and Zoe met on the set of new movie 'The Words' but only started dating after the 33-year-old actress split from her fiance Keith Britton in November.

The source added: "They're dating, but Zoe just left an engagement. She's just looking to have fun."

Bradley, 36, was named People magazine's Sexiest Man Alive last year and he proved the title was justified by romancing a bevy of famous beauties, including Renee Zellweger, Jennifer Lopez and Olivia Wilde.

However, the 'A-Team' star tried to play down his sex symbol status in the wake of receiving the honour.

He said: "Oh, it's just so awful. I'm finally at an age where I really don't care about anything like that anymore, which is wonderful thing, and then it happened. And then I started to realise just how not sexy I am.

"I have a lot of moments where I'm walking out and I'll open up the door and think to myself, 'I could do that a lot sexier'."