Mr Chemezov has been on a US sanctions list since April. The EU also imposed restrictions against Alexander Zakharchenko, currently the top-ranking rebel leader in Donetsk, who represented the separatists during last week's ceasefire negotiations, and Vladimir Zhirinovsky, head of Russia's far-right Liberal Democratic Party of Russia. As well as Gazprom, the US added restrictions to Lukoil, the privately owned oil group, and Sberbank, Russia's largest bank. The banks will be banned from securing dollar-denominated debt of maturities of 30 days or more, compared to 90 days under previous sanctions, and US citizens will be prohibited from dealing in new equity offerings. The US Treasury has also imposed sanctions on Gazprom, Gazprom Neft, Lukoil, Surgutneftegas, and Rosneft that prohibit the export of goods, services and technology supporting Russian deepwater, Arctic offshore and shale projects.