Oscar-winner Reese Witherspoon says she is baffled by reports of tension between her and co-star Vince Vaughn on the set of new holiday season comedy "Four Christmases."

Speaking in Beverly Hills ahead of the new film's US release on Wednesday, Witherspoon described towering "Wedding Crashers" star Vaughn as the "funniest man she has worked with."

"Every co-star I ever work with I'm either having an affair with him, I'm about to get married with him, or having a baby or we absolutely cannot stand each other," Witherspoon, 32, said of gossip reports.

"We got along great, we were very good friends and we were very much partners on this movie," added Witherspoon, who won an Academy Award in 2006 for her performance in Johnny Cash biopic "Walk the Line."

"Vince is the funniest person I've ever worked with. It was a challenge for me to stay there and keep up with him. But I feel really a better actor for that experience," she added.

The difference in height between Witherspoon and Vaughn -- he stands at 6ft 5in, she is a petite 5ft 2in -- did cause headaches.

In some dancing scenes Vaughn was required to carry Witherspoon in order for her to fit in the camera frame.

Witherspoon's latest role sees her and Vaughn play a couple who are forced to abandon their plans for an exotic Christmas vacation and must visit their four parents separately over the holiday period. The chaos that ensues forces them to re-examine their relationship.

Mother-of-two Witherspoon, who divorced actor Ryan Philippe in 2007 and who is now romantically linked to "Brokeback Mountain" star Jake Gyllenhaal, said she was attracted by the story of juggling family commitments at Christmas.

"I'd never seen anyone do the idea of the blended family and how they have to go to a million different places at Christmas," she said.

"But I hear people complain about it constantly and it's a situation my own children will have to deal with."

Source: AFP