He is a billionaire Russian oligarch who has been closely linked to Vladimir Putin for three decades. And for years Petr Aven also enjoyed the trappings of London high society, as a trustee and donor of the Royal Academy of Arts, as well as owning three multimillion-pound UK properties, including one in the ultra-wealthy Surrey enclave of Virginia Water. Now the Guardian has seen documents suggesting that, after Russia’s invasion of Ukraine, a Cypriot professional services firm helped wire about £3.7m into the UK from an Austrian account belonging to Aven. The funds left the Austrian account hours before Aven was publicly announced as being under EU sanctions and two weeks before he was added to the UK list – raising questions about the timing of the transfer to the UK. When placing the oligarch under sanctions on 28 February last year, the EU said: “Petr Aven is one of Vladimir Putin’s closest oligarchs … He is one of approximately 50 wealthy Russian businessmen who regularly meet with Vladimir Putin in the Kremlin. He does not operate independently of the president’s demands.” Aven has called the restrictions “spurious and unfounded”. Aven’s links to the Austrian account have emerged in previously unreported sections of publicly available UK court filings from a civil case brought against him and associates by the National Crime Agency (NCA). The tycoon has an estimated $5.5bn (£4.5bn) fortune. He owns Ingliston House, near Virginia Water, on 3.4 hectares (8.5 acres) of land in a gated estate next to Wentworth golf course. The house boasts some of the oligarch’s £300m art collection, including works by the Russian painter Wassily Kandinsky – plus a sculpture garden featuring pieces by Louise Bourgeois and Antony Gormley. The management of the estate was funded via a series of companies headed by Ingliston Management Ltd (IML), court papers set out. On the evening of Monday 28 February, the EU announced Aven had been added to its sanctions list, along with other oligarchs it said were connected to the Kremlin. Earlier that day, agents acting for an Aven trust sent £3.7m from an Austrian bank to IML’s account in the UK – with the money from the EU member state arriving days after EU sanctions had taken effect. Court documents relating to the freezing last year of the Aven-connected UK bank accounts state: “On 3 March 2022, the HSBC IML account received approximately £3.7m from an Austrian-based company, Dendar Investment Fund Ltd, believed to be controlled by Aven.” Most of the funds were then forwarded to other UK accounts controlled by Aven’s assistant, according to court filings, and the NCA moved to freeze the accounts suspected of containing Aven’s money, which it alleged were intended for use in “unlawful conduct, namely [UK] sanctions circumvention”. The court filings add: “This account activity was unusual and given that the transactions occurred four days after Mr Aven was sanctioned by the EU, it is suspected that their purpose was to disguise the fact that Mr Aven was the ultimate owner of the funds in order to circumvent anticipated UK sanctions.” The transfer into the UK was commenced a day after the EU’s most senior diplomat, Josep Borrell, said that new sanctions were imminent and likely to be active before the start of business on the following day. After issuing a press release, Borrell told a news conference on 27 February: “We want to take some decisions that should be in place, agreed, and in a legal act implementing them before tomorrow when the central banks will restart working.” Aven’s £3.7m transfer from Austria was then initiated the day after Borrell’s announcements – and only hours before the public notice that Aven had been placed under EU sanctions. However, the Council of the EU, the European Commission and sanctions lawyers have told the Guardian that the 28 February restrictions were legally active from the first minute of that day, raising questions over timing and whether EU sanctions may have been breached. A Council spokesperson said: “The entry into force occurred at the beginning of the first hour of the day of publication in the [Official Journal]. This means from the very first hour of 28 February.” The NCA has contradicted the EU’s interpretation and has said in court filings that it understands no EU rules had been broken, as the EU’s public sanctions announcement came after initiation of the money transfer. The court records were obtained by the campaign group Spotlight on Corruption and the International Consortium of Investigative Journalists, after petitioning the judge in the civil trial between Aven and the NCA, and were shared with the Guardian as part of the Cyprus Confidential project. Aven’s advisers said the tycoon was the beneficiary of the Dendar Investment Fund, according to the court filings, and that the transfer had been managed by offshore agents in Cyprus acting for Aven. The agents in question are not among those whose data was leaked. Material from the Cyprus Confidential files – which includes a leaked corporate registry – also suggests Aven is linked to Dendar. Aven’s lawyers said: “Our client does not consider it appropriate to comment on the matters you raise while they remain the subject of ongoing legal proceedings.” He has previously said there is no reasonable basis for any “purported suspicion” about the bank accounts, which provide living expenses for his family, and that the transfer was sent before EU sanctions were publicly announced. The tycoon is also appealing against the EU’s decision to place him under sanction. Aven is no longer a trustee of the Royal Academy – which returned a donation he made towards a Francis Bacon exhibition. The NCA civil case is continuing.