Billions of pounds linked to the Russian oligarch Alisher Usmanov and his business empire appear to have been held in secret Swiss accounts belonging to his family, an analysis of leaked documents suggests. Usmanov’s 56-year-old sister, Saodat Narzieva, appears to have been the one-time beneficial owner of at least 27 secret corporate accounts at Credit Suisse, including one that held nearly 1.9bn Swiss francs (CHF) (£1.6bn). Usmanov is subject to EU sanctions. Narzieva is a gynaecologist and obstetrician in a maternity hospital in Uzbekistan’s capital, Tashkent. Her name is attached to Credit Suisse accounts that appear in the Suisse secrets project, a leak of data relating to 30,000 clients of the Swiss bank. It is not clear why her name would be linked to accounts associated with her brother’s business empire. A spokesperson for Usmanov suggested the Credit Suisse data was “fake and incorrect” and there was nothing untoward about his financial relations with his sister, which were lawful and indicative of his “generosity”. Information from numerous financial leaks, including Suisse secrets, the Panama papers and FinCEN Files, has allowed reporters at the Guardian to highlight the vast wealth linked to Usmanov. The disclosures highlight the potential challenges western governments face when sanctioning or freezing the assets of oligarchs. The Russian Asset Tracker project has included relatives and associates, because in some cases their wealth derives almost entirely from the person under sanctions. Including family gives a more complete picture of the scale of their fortunes and, in some cases, they may have been used to hide or disperse assets. Last month, the US Treasury highlighted the problems of ownership by stating: “Sanctioned oligarchs and powerful Russian elites have used family members to move assets and to conceal their immense wealth.” Usmanov was worth an estimated $18.4bn (£14bn) in 2021 when he was listed as one of the world’s 100 wealthiest people by Forbes magazine. When the Guardian first asked Usmanov about links between the Credit Suisse accounts showing his sister as a beneficiary and his business group on 15 February, before Russia’s invasion of Ukraine, he instructed the London law firm Schillings to respond on his behalf. At the time, they said “true or false, information about a person’s finances is private. We can see no reason at all for our client to discuss financial dealings with journalists.” Schillings did not respond when asked whether the firm still represented the oligarch. The spokesperson for Usmanov has since stated that Narzieva did not have “possession or control of any accounts in Swiss banks on behalf of her brother”. “Any financial relations of Mr Usmanov with his sister would have been [the] result of his well-known generosity and support that he has always lawfully lent to his relatives,” they said. His spokesperson added that “all of Mr Usmanov’s businesses have been audited by Big 4 [audit] companies, since their inception, as well as were his personal tax returns and expenses. All of his investments, his expenses and his income have gone through strict compliance procedures.” Usmanov, an Uzbek-born businessman, has been subject to an asset freeze and EU travel ban since late February, after the bloc identified him as “one of Vladimir Putin’s favourite oligarchs” who it is claimed has paid millions to one of Putin’s influential advisers and been “entrusted with servicing financial flows”. Usmanov accused the EU of “false and defamatory allegations” that were “damaging his honour, dignity and business reputation”. Sanctions have also been imposed on him in the US and UK, where he once held a 30% stake in Arsenal football club. Switzerland has followed suit, ditching political neutrality to match the EU’s efforts. While western governments have introduced sanctions against the relatives of some Russian oligarchs, none of Usmanov’s family members have been included on any lists so far. According to documents in the Suisse secrets data, the 27 accounts at Credit Suisse that listed Narzieva as the beneficial owner were opened between 2004 and 2014, and 16 listed Usmanov’s metals, mining and telecoms holding company, USM, as a contact. The largest of the accounts held nearly 1.9bn CHF in 2011, while two others held up to 1.3bn CHF and 460m CHF in 2014. While a handful of the accounts were closed by 2016, about 18 are believed to have still been active in recent years. All of the assets were held in business accounts, some of which are believed to be linked to offshore companies. Credit Suisse said it was unable to comment on the accounts because of Swiss banking secrecy laws, and said it applies all sanctions “as a matter of principle and policy.” Narzieva’s brother made his fortune producing plastic bags, which were a rare commodity in the former Soviet Union, and later went on to manage the investment holdings arm of Russia’s state-owned gas company Gazprom from 2000 to 2014. He built stakes in a range of metals, mining, telecom and media firms through USM, which owns Russia’s second-largest mobile phone operator, MegaFon, as well as a 49% stake Metalloinvest, the metals and mining company Usmanov founded in 1999. A leaked email from the Panama papers lists Narzieva as one of several close relatives for whom offshore companies were being set up in 2013, in order to hold shares in another of Usmanov’s holding companies, ABU. The email, sent by the now-defunct Panamanian law firm Mossack Fonseca, suggested that each of the so-called special purpose vehicles would hold bank accounts with Credit Suisse and another Swiss bank, Julius Baer. According to documents reviewed by the Guardian, one American bank raised suspicions about $1.6m-worth of transfers made between accounts linked to Usmanov and his associates between 2003 and 2015, including through one of the Credit Suisse accounts that named Narzieva as a beneficial owner. The bank reported that there were suspicions on the grounds that the company at the centre of the report – Usmanov’s Cyprus-based Gallagher Holdings – appeared to be a shell company that conducted “a significant amount of wires with numerous other shell entities”. The suspicious activity report (SAR) – filed in 2016 and later obtained by BuzzFeed and the International Consortium of Investigative Journalists – said the bank could not determine the purpose of some of the transactions. The SAR added that it was concerned that “Gallagher appears to be owned by individuals with connections to Putin.” Banks and other financial institutions file SARs with law enforcement bodies when they suspect a client may be using their services for potential criminal activity. However, SARs do not mean a client is guilty of wrongdoing or require a bank to cease doing business with the client. A separate SAR filed in 2017 suggested Usmanov was the original source of more than $2.5m that Narzieva used to send money to a steel company boss in the Middle East in 2013. According to the SAR, Narzieva appears to have forwarded the money to the Middle Eastern businessman shortly after Usmanov wired his sister a “gift” of $3m. She later sent at least $50,000 back to Usmanov – which was related to “current expenses”, according to the payment reference. That businessman was the boss of a joint venture established by Usmanov’s Metalloinvest in 2010. The bank said in the SAR that it could not establish the purpose of the wire transfer between Narzieva and the Middle Eastern businessman since they “appear to be engaged in different lines of business as a doctor and managing director of a steel company, respectively”. The spokesperson for Usmanov and Narzieva did not explain the purpose of the transfer but said the Middle Eastern businessman was her son-in-law. Usmanov’s spokesperson said: “The entirety of Mr Usmanov’s capital was built through successful, sometimes risky, investments, as well as through the effective management of his assets, which is the essence of business.” The representative also stressed that, unlike some other wealthy Russian businessmen, Usmanov did not gain his fortune by acquiring newly-privatised Russian assets following the end of the Soviet Union They added: “Mr Usmanov has never acquired anything nor has he benefited from the Russian government, or that of any other state.”