The European Union has imposed sanctions on a Russian oil boss who is separately alleged by the US authorities to be acting as a “straw owner” of two yachts linked to Vladimir Putin and his inner circle. Eduard Khudainatov served as chairman and chief executive of the state-controlled oil company Rosneft before setting up his own energy business, Independent Oil and Gas Company, which has grown rapidly to become one of Russia’s top oil producers with interests in extraction, refining and trading. The EU said the 61-year-old businessman was associated with Putin, whose first presidential campaign he helped to organise in 2000, and his close ally Igor Sechin, who succeeded Khudainatov at the head of Rosneft. It said he had been blacklisted for “benefiting from the government of the Russian Federation” and being “associated with listed persons”. Sechin and Putin have been under EU sanctions since the invasion of Ukraine. Khudainatov has kept a low profile compared with Russian oligarchs such as Roman Abramovich. However, since the invasion he has come to international attention after being named in a court case as the owner of two luxury vessels – the $325m (£260m) Amadea and the $700m Scheherazade. The European sanctions listing did not reference Khudainatov’s alleged ownership of the superyachts. The Amadea is the subject of a legal battle in Fiji, where it was seized on 19 April at the request of the US government, which claims it belongs to the sanctioned Russian oligarch Suleiman Kerimov. A trail of offshore companies and trusts reportedly links Khudainatov to the Amadea and to the Scheherazade, which is alleged to have been used by Putin. Lawyers acting for the British Virgin Islands company that owns the Amadea have told the court the legal owner is Khudainatov. However, according to court filings seen by US media, the American government has dismissed Khudainatov as a “straw owner” who it says is standing in for the real owners of both vessels. Fiji’s supreme court is set to rule on the case on 7 June. The Scheherazade, which has six decks and two helipads, was seized by the Italian government in May. It had been undergoing repairs in the port of Marina di Carrara, and police swooped amid concerns it was about to set sail. In a statement announcing the seizure order, the Italian finance ministry did not name the owner, saying only that he had ties to “prominent elements of the Russian government”. The organisation set up by the imprisoned Russian opposition leader Alexei Navalny released a report in March saying it had evidence that the Scheherazade belonged to Putin. Both yachts were reportedly managed and crewed by the Monaco-based specialist Imperial Yachts. The company was named in US sanctions on Thursday night along with its owner, Evgeniy Kochman. The US treasury department said Kochman’s company “provides yacht-related services to Russia’s elites, including those in President Putin’s inner circle”. It identified four yachts “favoured by Putin” – the Nega, the Graceful, the Olympia and the Shellest – that the Russian leader had “taken numerous trips on”, including as recently as last year. The Scheherazade was not named in the statement. Khudainatov’s oil business has acquired significant stakes in companies involved in the energy sector, together with their extraction licences, from the state-owned Rosneft, according to the EU sanctions listing. In the last few years Rosneft has paid $9.6bn to Khudainatov in exchange for a company that owns an oilfield in Taymyr, it said. It was not possible to reach Khudainatov for comment.