As we were reporting yesterday, Jennifer Aniston was photographed with co-star Vince Vaughn in a Chicago park during a break from shooting the upcoming movie "The Break Up". And it appears the two actors did more then smoking a cigarette together.

They were photographed kissing, with Jennifer in Vince's arms. An onlooker is quoted in Britain's Daily Mirror newspaper as saying: "They seemed very comfortable in each other's company and were quite spontaneous when they hugged."

Another witness told Britain's Daily Mail newspaper: "They were being photographed by a friend on a small pocket camera and they were also taking pictures of themselves.

Although they appeared to be hamming it up for the camera, there was definitely a frisson of flirtation. They were holding on to each other for much longer than they needed to and they could not stop grinning at each other", the witness added.

This is not the first time Jennifer Aniston and Vince Vaughn are pictured together. During the last weeks, the two actors were photographed cuddling on the set of "The Break Up" and at Vaughn's Four Seasons hotel in Chicago, where it is rumoured Jennifer spent the night with the actor.

Both Aniston, 36 and Vince, 35, repeatedly denied any romantic implication, declaring they are only good friends.