The UK government has imposed sanctions on the “financial fixers” who have allegedly helped the Russian oligarchs Roman Abramovich and Alisher Usmanov hide their assets. The sanctions, announced by the Foreign Office on Wednesday, are targeted at what officials describe as “oligarch enablers”, whom they accuse of knowingly assisting the billionaire businessmen to shield their wealth. The latest round of restrictions include asset freezes and travel bans on two Cyprus-based individuals alleged to have provided services to Abramovich and Usmanov. The measures come after the Guardian’s Oligarch files project revealed in January that trusts holding billions of dollars of assets for Abramovich, the former owner of Chelsea football club, were rapidly reorganised shortly before sanctions were imposed on him. They are the latest round of asset freezes and travel bans the UK has imposed on close associates of Abramovich and Usmanov, both of whom were hit with sanctions last year shortly after Russia invaded Ukraine. After the UK announcement, the US Treasury published wide-ranging restrictions targeting Usmanov’s associates and “facilitators” alleged to have helped manage his financial interests. UK officials have said that in response to an unprecedented package of international sanctions, oligarchs “scrambled to shield their wealth with the help of financial fixers, offshore trusts, shell companies, and even using their family members”. According to leaked files seen by the Guardian, 10 of Abramovich’s secretive offshore trusts were amended to transfer beneficial ownership to his seven children in the weeks leading up to the invasion, raising questions about whether the changes were made to shield the oligarch’s vast fortune from the threat of asset freezes. Documents suggest the sweeping reorganisation was executed by Demetris Ioannides and his company, who has helped manage Abramovich’s financial interests for more than 20 years. The UK has now imposed sanctions on Ioannides and the offshore service provider he runs, MeritServus HC Ltd. Ioannides is accused by UK officials of “crafting the murky offshore structures which Abramovich used to hide over £760m assets ahead of being sanctioned”. UK and EU officials have cast Abramovich as a pro-Kremlin oligarch and last year imposed sanctions on him for allegedly benefiting from close relations with Putin. Abramovich has denied financial ties to the Kremlin and filed legal action to overturn the EU’s measures. In the new package of measures, Whitehall officials have also focused on the complex financial holdings of Usmanov, a Russian metals magnate, and imposed sanctions on companies and associates linked to him. This includes Christodoulos Vassiliades, a Cypriot lawyer, alleged to be “at the centre of a web of trusts and offshore companies” that link Usmanov to Sutton Place, a Tudor manor in Surrey. Neither Ioannides nor Vassiliades responded to the Guardian’s requests for comment. In a statement, Usmanov’s holding company USM said it intended to challenge the restrictions. “We consider the UK sanctions adopted against USM and its shareholders to be unjust and unfounded.” The new steps indicate the UK government is prepared to expand its Russia sanctions regime to include “enablers”, whom it has characterised as professional advisers and intermediaries who facilitate sanctions evasion and associated money laundering. In July UK enforcement agencies said some individuals who had been placed under sanctions were using enablers to distance themselves from their assets by, for example, transferring ownership to trusted intermediaries such as family members. A former senior US sanctions enforcement official said the focus on “professional enablers” by authorities in London and recently in Washington represented a new development, though they had long had legal powers to target those providing material support to individuals who had been subjected to sanctions. “Given the focus on oligarchs,” the former sanctions officials said, “this is the next obvious step because of the way these individuals have relied heavily on a network of people in the service sector to access finance and the life they would like to live.” The latest round of measures has imposed restrictions on family members and associates alleged to be acting as proxies for oligarchs under sanctions, including Viktor Medvedchuk, an ally of Putin. Announcing the measures, the British foreign secretary, James Cleverly, said the government was “closing the net on the Russian elite and those who try to help them hide their money … We will keep cutting them off from assets they thought were successfully hidden.”