Socialite Paris Hilton is said to have had a horrific row with boyfriend Doug Reinhardt on Halloween after he tossed her cellphone out of their limousine.

The two were enjoying the annual costume party thrown by Heidi Klum and Seal on October 31, but after they left the event, they allegedly became embroiled in a furious row as they got into their car.

“She was mad. She jumped in the front seat and (Doug) was holding her around the neck saying, ‘Relax, relax’,” the Daily Star quoted witness Ramon Alves as telling the New York Post.

The argument then reached a climax when Reinhardt allegedly threw the hotel heiress’ cellphone through the car window - forcing Hilton to stop the vehicle and search for the device.

“She was staggering down the street, up and down. And the guy they were with was trying to block anyone from taking pictures. It got very physical. The limo driver was horrified!” a second witness added.