London (CNN) -- Celebrity chef Nigella Lawson spoke out angrily Friday against what she said were false claims of habitual drug use made against her in the trial of two former personal assistants.
Sisters Elisabetta and Francesca Grillo were each cleared of fraud Friday by the jury in the London court that heard the case.
Francesca Grillo had been accused of defrauding Lawson and her ex-husband Charles Saatchi of 580,000 pounds ($950,000), and Elisabetta Grillo of defrauding them of 105,000 pounds ($172,000). Both had denied the charges.
The case has gripped UK media, thanks to revelations of drug use by Lawson and insights into her troubled marriage to Saatchi, a millionaire art collector. The couple divorced this year.
Lawson, who was a prosecution witness, said she was "disappointed but unsurprised" by the verdict, and she slammed what she said was a sustained campaign to ruin her reputation.
"Over the three week trial the jury was faced with a ridiculous sideshow of false allegations about drug use which made focus on the actual criminal trial impossible," she said in a prepared statement.
"My experience as a witness was deeply disturbing. When false claims about habitual drug use were introduced I did everything possible to ensure the (Crown Prosecution Service) was aware of the sustained background campaign deliberately designed to destroy my reputation."
Lawson called for reform to the judicial system to allow witnesses to rebut false claims against them.
"I did my civic duty, only to be maliciously vilified without the right to respond," she said.
"Even more harrowing was seeing my children subjected to extreme allegations in court without any real protection or representation. For this I cannot forgive the court process."
The TV chef said she had voiced her regret during the trial about having to talk about the end of her 10-year marriage.
She said she'd also expressed concern about "a campaign to circulate false allegations" over the course of the past summer and eventually in court, as part of the sisters' defense. "That concern remains," she said.
At the trial, both sisters claimed to have seen signs of repeated cocaine and cannabis use by Lawson.
However, both testified that they had never seen her take drugs. Saatchi likewise said he had never seen his ex-wife use drugs.
Elisabetta Grillo told the court that Lawson had smoked cannabis with her two children from her marriage to her first husband, the late John Diamond.
In her own testimony, Lawson confirmed she had taken cocaine half a dozen times, during two periods of her life, and used cannabis in the past. But she denied being a habitual user.
London's Metropolitan Police Service said Friday that it had no plans at this stage to investigate allegations of drug use made at the trial. The decision could be reviewed if any evidence that could be investigated comes to light, it said.
'Long, hard fight'
Neither defendant was in the dock Friday to hear the verdict because of Elisabetta Grillo's ill health.
Richard Cannon, a lawyer for the sisters, gave a statement on their behalf outside court.
"This has been a long, hard fight played out in the gaze of the world's media," he said.
"Elisabetta and Francesca would like to thank friends and relatives for their love and support and members of the public who expressed their best wishes."
Cannon said Elisabetta was "very well."
The two sisters still face a civil case brought by Saatchi.
In summing up, the judge told the jury that they must weigh up whether the prosecution had proved in the case of each of the sisters that they had acted dishonestly and knew they were acting dishonestly.
The defense argued that the sisters had explicit and implicit authorization for their personal expenditure.
During the trial, the Italian sisters told Isleworth Crown Court in west London that Lawson authorized their personal expenditures on Saatchi's company credit cards, including on designer shoes, clothes and trips abroad.
Both defense lawyers questioned Lawson's credibility as a prosecution witness and said their clients' claims that she repeatedly used drugs were relevant to that issue.
Jane Carpenter, giving the prosecution's closing argument in the case, said Thursday that the sisters had abused their position "time and time again" and that they "grew bolder and greedier" as time went by.
The prosecution outlined dozens of transactions that it said were unauthorized by Saatchi or Lawson.
CNN's Antonia Mortensen contributed to this report.