Claims that the self-styled Domestic Goddess was a habitual cocaine and cannabis user emerged during the trial of two personal assistants who were cleared Friday of defrauding Lawson and her ex-husband, the millionaire art collector Charles Saatchi.
Lawson, 53, insisted during the trial that she was not addicted to drugs and had only used cocaine and cannabis occasionally in the past.
London's Metropolitan Police said after the verdict that they would not be investigating the drug claims.
But today the force said a team of specialist officers would be reviewing the evidence, though there is "no imminent prospect" of Lawson being prosecuted.
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"On that basis therefore, and in absence of any other corroboration, there is no imminent prospect of a prosecution being mounted.
"As we said however, should any evidence come to light that can be investigated further, we will review this decision."
Lawson, who has made millions with her TV series and cookbooks in Britain and the United States, is battling to restore her reputation after a trial which saw details of her private life splashed across the newspapers.
The glamorous TV chef had lashed out at Saatchi in court for claiming she was so "off her head" on drugs that she had allowed the Grillos to spend whatever they liked.
Lawson had told the court she had only taken drugs during two periods of her life.
She said she took cocaine with her first husband John Diamond just before he died of cancer in 2001, as well as in 2010 when she was having a "very, very difficult time" in her marriage to Saatchi.
The couple's decade-long marriage ended this year after shocking photographs emerged of Saatchi gripping Lawson around the throat at a London restaurant.
Saatchi, 70, accepted a police caution over the incident but insisted he had not been violent.