'Of course now the Grillos will get off on the basis that you (and) Mimi were so off your heads on drugs'
The accusation came in an email from Saatchi ahead of the trial of two of the former couple's personal assistants.
Francesca and Elisabetta Grillo are accused of using company credit cards to spend £300,000 on luxuries including designer clothes and first-class air travel.
Today Judge Robin Johnson read out an email sent from Saatchi to his former wife in court, accusing Nigella and her 19 year-old daughter Cosima, known as Mimi, of taking drugs.
The email read: 'Of course now the Grillos will get off on the basis that you (and) Mimi were so off your heads on drugs that you allowed the sisters to spend whatever they liked and yes I believe every word they have said.'
Asked by the police to explain what he meant in his message, Saatchi said: 'At the time of sending that email I was completely astounded by the alleged scale of drug use set out in the statement.
'Nevertheless, I did believe the allegations and that's what I'm referring to in the email.
'I have been asked whether it referred to a belief that Nigella or the children permitted the sisters to spend whatever they liked. I can't remember precisely what I had in mind. On reflection I was simply speculating that the sisters would use this information to defend themselves.
'I know there was nothing in the statement to suggest they were given permission to use the cards.'
The explosive allegations were made as Judge Johnson allowed ‘bad character’ evidence against Nigella to be heard at the upcoming trial of the sisters.
TV chef Lawson is expected to give evidence during the trial, which was not expected to start on Tuesday. The judge said the email could be reported, despite the trial not having yet begun.
Judge Johnson said Saatchi was asked by police to explain what he meant in the message to the TV chef.
The judge told the court that Saatchi said: ‘At the time of sending the email I was completely astounded by the scale of drug use set out in the statements (from the defendants).
‘Nevertheless I did believe the allegations that I'm referring to in the email. I have been asked whether it referred to a belief that Nigella or the children permitted the sisters to spend whatever they liked. I can't remember precisely what I had in mind.
‘On reflection, I was simply speculating that the sisters would use this information to defend themselves.’
Defence barristers acting for the two defendants had wanted details of the alleged drug use by Lawson - who ended her 10-year marriage to Saatchi earlier this year - to be heard in the case.
The judge concluded: ‘I will allow questions of Miss Lawson and witnesses as to the alleged taking of prescribed drugs or proscribed drugs.’