Chris Martin's alleged make-out session with actress Kate Bosworth “simply never happened”, according to the latest reports.

Gwyneth Paltrow's husband stunned fellow guests at an unspecified event by locking lips with the actress, according to an 'eyewitness' quoted in a US tabloid.

"I couldn't believe my eyes," the source told Star magazine. "There was Chris totally making out with Kate in front of other people.

“At first I thought it might be Gwyneth, but when she came up for air, it was clear the woman was Kate!"

But a rep for the Coldplay singer tells Usmagazine.com: "This story is entirely untrue."

A source adds that the kissing incident, "simply never happened. She may have been in the same room with him, but he is not having an affair, was not kissing her or holding her hand."

Chris and Gwyneth - who are rarely seen in public together - have been dogged by tales of marital woe throughout their six-year-old marriage.