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Two personal assistants of British television chef Nigella Lawson and her art dealer husband Charles Saatchi say they were treated “worse than Filipino slaves” despite defrauding the couple of more than STG685,000 ($A1.2 million), a court has been told.

Italian sisters Francesca and Elisabetta Grillo face fraud charges in a trial that has already featured allegations that so-called “domestic goddess” Lawson hid a long-term cocaine and cannabis habit.

Saatchi, 70, arrived at court but there was no time for him to give evidence on Thursday, while his now ex-wife Lawson, 53, is also expected to testify at a later date in the trial at Isleworth Crown Court in west London.

Multi-millionaire Saatchi’s finance director Rahul Gajjar told the jury that he confronted the Grillo sisters over their alleged use of the celebrity couple’s credit cards to spend STG685,000 ($A1.24 million) on a luxury lifestyle.

Francesca Grillo was spending a monthly average of STG48,000 while Elisabetta Grillo was spending an average of STG28,000, Gajjar said. Saatchi’s other assistants were spending a maximum average of STG8,000 a month.

They bought themselves flights, hotels and designer goods by brands including Louis Vuitton, Christian Dior, Vivienne Westwood, Marc Jacobs and Calvin Klein.

When confronted by Gajjar, Francesca, 35, and Elisabetta, 41, were at first apologetic and Saatchi agreed to let them remain in his employment and to keep living rent-free at a flat owned by Lawson, the finance director said.

But when Gajjar wrote to them outlining how they might pay off their debt they became agitated, he said.

“Lisa was against the proposal and I remember a reference to ‘We’re being treated worse than Filipino slaves’,” Gajjar said.

Saatchi and Lawson then went to the police after they failed to reach an agreement with the two sisters.

The Grillos deny fraud.

Their lawyers had argued unsuccessfully on Wednesday that the charges should be dropped because allegations about Lawson’s alleged drug use that emerged during the proceedings damaged her credibility as a witness.

The court saw documents from Saatchi on Tuesday in which he described Lawson as “Higella” and said she was so “off her head” on drugs that her assistants were able to go on spending sprees with her credit card.

Anthony Metzer, representing Elisabetta Grillo, had said that if claims by Saatchi about Lawson’s drug-taking were true it would make her a “habitual criminal”.

Saatchi and Lawson split after 10 years of marriage earlier this year.

They announced their divorce after shocking pictures appeared in British newspapers of Saatchi grabbing Lawson by the neck outside a London restaurant.