London ( CNN ) -- Two former personal assistants to celebrity chef Nigella Lawson and her ex-husband Charles Saatchi splashed out on luxury goods on company credit cards , a court heard Thursday . The former assistants , Italian sisters Francesca and Elisabetta Grillo , are accused of fraud . They deny embezzling hundreds of thousands of pounds from the couple . The first witness , Rahul Gajjar , an accountant for Saatchi , told the court in west London that Francesca had 64,336.97 pounds ( $ 104,500 ) in expenses on her company credit card in June 2012 . Among the expenses were purchases from designer labels Prada , Miu Miu , Louis Vuitton and Chloe as well as hotel bills and plane tickets . The court heard that Francesca 's average monthly expenditures were 48,000 pounds and Elisabetta 's were 28,000 pounds , whereas other personal assistants for Saatchi , a well-known art collector , spent 8,000 pounds or less a month . Gajjar said he noticed the sisters ' credit card balances had changed at the beginning of 2012 . Their average monthly expenditures were previously between 10,000 pounds and 20,000 pounds a month , he said . He was more concerned about Francesca 's balance because it was higher , he said -- reaching about 40,000 pounds `` on a regular basis . '' The prosecutor asked why he did not raise the matter with Saatchi and Lawson immediately , but Gajjar said he put it `` on the back burner '' because other matters were more pressing . `` We were dealing with more corporate matters -- more serious corporate matters -- and Mr. Saatchi and Miss Lawson normally did n't have time for what we thought were trivial matters , '' Gajjar said . The sisters were expected to make purchases for the family on the company credit card , he said , as part of their job helping the couple with personal and work-related matters . He said they had a close relationship with Lawson and Saatchi and regularly accompanied the family on holiday . After an investigation revealed the sisters ' alleged personal spending , Gajjar said he met with them in July 2012 to discuss the situation . The sisters , who did n't have any housing expenses , initially said they were `` happy to start paying back '' what they had spent on themselves , he said . However , they then rejected the offer and complained of their treatment , he said . Saatchi 's testimony had been expected to follow that of Gajjar , who has been finance director of the Saatchi Gallery Group , part of the multimillionaire art dealer 's Conarco Partnership , since June 2002 . However , it became clear there would not be time for Saatchi to take the stand before proceedings finished for the day . Saatchi is expected to testify Friday . Drugs use allegations . Isleworth Crown Court heard at a pretrial hearing for the sisters this week that Lawson and Saatchi had a `` culture of secrecy '' around their marriage . In the hearing , the defense read an e-mail from Saatchi to Lawson about the allegedly embezzled money , saying the assistants would `` get off '' because , he wrote , Lawson was using cocaine and marijuana on a daily basis and `` allowed the sisters to spend whatever they liked . '' Representatives for Lawson declined to comment on the allegations , citing the ongoing court proceedings . The defense also read a statement from Saatchi saying he learned of Lawson 's alleged drug use in June , around the time the couple were photographed in a restaurant having an argument . In the photos -- which were splashed across the front pages of national newspapers at the time -- Saatchi is seen with his hand around Lawson 's throat . Saatchi accepted a police caution for assault , and the couple announced they would divorce soon afterward . The defense alleged that the e-mails showed both Saatchi and Lawson had attempted a `` manipulation of the court '' and that the case should be thrown out . The judge ruled the trial would proceed . The prosecution told the court Wednesday that the two sisters spent some 685,000 pounds ( $ 1.1 million ) on company credit cards over the course of four years , according to UK media reports . The pretrial hearing had heard allegations the two sisters had spent a lesser amount , about 300,000 pounds , on luxuries . On Wednesday , Lawson tweeted out a recipe , saying it was in thanks for her supporters . `` Holiday Hotcake : the perfect recipe to show thanks for all your support & to those who hashtag # teamNigella , '' she wrote . Lawson , whose culinary skills have long entranced UK audiences , has also appeared as a judge on ABC show `` The Taste '' in the United States . A second season of the show is due to air in January . Opinion : The rich and famous are not immune to domestic abuse . CNN 's Atika Shubert contributed to this report .
NEW : Testimony from Charles Saatchi , Nigella Lawson 's ex-husband , is expected Friday . The trial of the former couple began in London on Tuesday and will continue over two days at London's Old Bailey court house before a jury returns its verdict next week. Lawson 's reps have declined to comment on drug use allegations made in court . The couple 's former assistants deny embezzling large sums of money .