Supermodel Naomi Campbell allegedly slapped one of her assistants across the face during a trip to Brazil.

According to the New York Post, when the sobbing assistant threatened to report the incident to the police, Campbell warned that she would leave her stranded in South America.

According to a source, "Naomi was slapping her with one hand. She then told her, 'If you go to the police, you're going to have to pay for your airfare home and I'm going to whack you with this big hotel bill.'"

"They were staying at an expensive suite in Rio and the assistant couldn't afford to pay for any of that. She's still travelling with Naomi, but she wants to quit as soon as they come back to New York."

Campbell's spokesman insisted that the story was "absolutely not true".

In 1999, Campbell reportedly spent a month at an anger management clinic. In 2000, Campbell pleaded guilty to beating her assistant with a cell phone and in 2004, her maid Millicent Burton had to go to hospital after she had a spat with the fiery supermodel over packing a suitcase.