Katherine Heigl has been accused of behaving like a diva while filming '27 Dresses'.

The 30-year-old actress reportedly refused to film any scenes on the 2008 movie unless she was brought a can of Coke Zero, and also refused to talk to extras on set.

An extra on the film told gossip blogger Perez Hilton: "She wouldn't film any scenes until her pregnant assistant ran and got her a Coke Zero. She refused to eat lunch next to anyone or have anyone speak to her once the cameras stopped rolling.

"I filmed RIGHT next to her. for 10 hours straight two days in a row and she never once said hello to me. Never even looked in my direction even after I tried to make conversation."

The new claims come after it was reported Katherine made a series of unreasonable demands on the set of her movie 'Five Killers'.

A crew member said: "She's had appointments with us - from camera tests to fittings - that she just hasn't shown up to and has been making herself unavailable.

"She and her mother, who is her manager, even had the audacity to request that wardrobe people go to her. We accommodated that request and she flaked on the meeting."

The movie is being shot in Atlanta and France, and Katherine has reportedly requested a private plane transport her to set and a large security team.

Another source said: "She has a sense of entitlement that is really off-putting. Many directors that she's worked with in the past DO NOT want to work with her again."