More than £35 million ($46.7m) disappeared from the account of a Russian billionaire’s son because of risky stock market trading made while at university and not because he was trying to hide assets from his mother, a London court was told. The finances of Temur Akhmedov, who the court heard was given a £29m flat by his parents while studying at the London School of Economics as a teenager, lie at the heart of the latest legal wrangling emanating from Britain’s largest divorce case. Mr Akhmedov is being sued by his mother, Tatiana Akhmedova, 48, who says her son owes her nearly £70m and accuses him of wholeheartedly abetting his father, Farkhad, in evading a £450m court-approved divorce settlement. Farkhad Akhmedov has refused to pay out to his former wife, who is pursuing cases in at least six countries. Their son claims his mother was aware of losses he had incurred through what he described as risky trading and had even consoled him afterwards. “That the sums were astronomical is nothing to the point,” Temur’s lawyer Robert Levy said. “Some of the extremely rich lavish their children with unimaginable sums. That is what Farkhad and Tatiana did during their marriage.” Farkhad made much of his wealth from the $1.4 billion sale of his stake in a Russian gas producer in November 2012, and Mr Levy told the court that Temur was given a £100,000 Mercedes car for passing his driving test when he was 17. Ms Akhmedova said she had been forced to pursue her son because he had aided her former husband in hiding assets from her, the High Court in London heard. “Temur just played an extremely active role in siding with my ex about the divorce,” she told the judge. The legal battle has involved unsuccessful attempts to seize a 115-metre yacht once owned by Chelsea FC owner Roman Abramovich and more than $140m of art stored in Liechtenstein. Temur’s apparent wealth is central to the case and his mother’s legal team is appealing for the court to order the sale of his London apartment, bought for £29m. “For me, day-trading equals gambling,” Tatiana said as she gave evidence in front of Judge Gwynneth Knowles on Monday. Temur has denied trying to keep the money out of reach of his mother. But Tatiana said her eldest son was involved in the plan as early as September 2015, before the divorce ruling the following year. “If the Tatiana problem did not exist, my father would not move his assets anywhere,” Temur wrote in an email at the time.