"She didn't seem to say much, but she did not look happy," a witness told the Daily Mail. "She could not get on the flight so she had to turn around and leave."
The specific grounds on which the reality TV star was barred entry to the United States have not been confirmed although prior drug abuse is widely reported to be the reason.
A Lawson representative told the newspaper, "We would never comment on Nigella's travel plans."
During a trial late last year, Lawson testified against her two former personal assistants Francesca Grillo and Elisabetta Grillo, who had been arrested and charged with swindling Lawson's now ex-husband Charles Saatchi, 70, out of nearly $500,000.
The Grillo sisters claimed Lawson allowed them to use Saatchi's company credit card in return for their silence about her alleged drug abuse.
Lawson was therefore forced to admit in court she had occasionally smoked cannabis and used cocaine in order to counter the accusation against her that she had been abusing drugs for more than 10 years.
Lawson subsequently told People in December she was completely drug-free and Good Morning America she was mortified about her private life being "distorted" and put on public display.
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