Ukraine has imposed sanctions on Dmitry Firtash, who formerly had business partnerships with Russia’s Gazprom, in a further crackdown against Ukrainian oligarchs with ties to Moscow.

Firtash, who has been in exile in Vienna since 2014, from where he is fighting extradition to the US on corruption charges, is regarded as Ukraine’s second most influential Kremlin-linked tycoon.

Friday’s moves mark the most recent step by Zelensky to try to break the hold of the oligarchs on the country.

“Today’s actions [are] a message to Moscow that they can no longer use favoured oligarch cut-outs to pursue their policy agenda,” an adviser to Zelensky told the Financial Times.

President Volodymyr Zelensky this year sanctioned Viktor Medvedchuk, who heads Ukraine’s top pro-Russian party and is a close friend of Russian president Vladimir Putin. Television channels thought to be controlled by Medvedchuk were shut down and the businessman was charged with treason — which he denies.

“As for Firtash, he is involved in the titanium business . . . the supply of raw materials that then goes, and this is tracked by our spies, to enterprises of the Russian Federation which are sanctioned by us,” said Oleksiy Danylov, Zelensky’s national security chief. “We cannot allow this to continue. It continued for a long time . . . to military enterprises.”

Ukraine has imposed a vast array of restrictions on businesses dealing with Russia since its northern neighbour annexed Crimea in 2014 and fuelled a separatist war in the far-eastern Donbas region.

There was no immediate comment from Firtash or his companies, which now face asset freezes and potential asset seizures.

Firtash has denied US allegations that he bribed Indian officials to obtain titanium mining licences.

Despite living abroad, Firtash owns chemical, energy and media businesses in Ukraine. His companies were involved in trading gas between Gazprom, Ukraine and European markets. Several of his close associates serve as MPs in Medvedchuk’s Opposition Platform — For Life party.

Also sanctioned in response to activities related to natural resource licences on Friday was Pavel Fuchs, a Ukrainian-born oligarch who made a fortune in Moscow’s property market but has since become prominent in Ukraine. He told Ukrainian TV that he would contest the sanctions.

Zelensky this month submitted to parliament so-called “de-oligarchisation” legislation that, if adopted, would require oligarchs to register, disclose assets, stop funding political parties and report contacts with public servants.

Expectation has mounted that the next target will be Igor Kolomoisky, who backed Zelensky’s presidential campaign. Zelensky has since distanced himself from Kolomoisky, who was sanctioned by the US this year for allegedly laundering proceeds funnelled out of PrivatBank, Ukraine’s top lender, which he then co-owned, into US property.

PrivatBank was nationalised in 2016 after authorities uncovered a $5.5bn balance sheet hole. Several top managers who served at PrivatBank under the ownership of Kolomoisky and his partners have recently been charged. Kolomoisky has denied wrongdoing.