Austria’s highest court has upheld a decision making it possible to extradite Dmytro Firtash, a Ukrainian tycoon facing bribery-related charges in the US.

Before his arrest in 2014, Firtash wielded significant political influence in Ukraine, where he had made a fortune from deals to import gas from Russia and central Asia and built a business empire worth billions. He was a close confidant of the former Ukrainian president Viktor Yanukovych, who was ousted in the Maidan revolution in February 2014.

A US grand jury indictedFirtash and five others on suspicion of bribing Indian government officials in deals involving supplies of titanium that could have affected the aircraft manufacturer Boeing.

Firtash has denied any wrongdoing and has said the charges against him are politically motivated. His lawyers have also said the US should not have jurisdiction in the case. In 2015 an Austrian court agreed, declining a US request for extradition, but that decision was reversed by a higher court in 2017 and the reversal was upheld on Tuesday.

“We are disappointed in today’s decision by the Austrian supreme court,” his lawyers said in a statement. “In any event, nothing has changed regarding Mr Firtash’s innocence and the absence of evidence that he is guilty of any crime.”

Austria’s justice minister will make a final decision on whether to turn Firtash over to a federal court in Chicago.

Firtash posted a record bail bond of £100m but was barred from leaving Austria while the extradition case was ongoing.

Firtash’s arrest has largely kept him out of politics in Ukraine since the 2014 revolution, leading to speculation that the criminal case against him was politically motivated.

In a 2016 interview with the Guardian, Firtash denied pushing Russian interests in Ukraine but said he had called on others to have closer talks with Russia.

“I told everyone we should bring Russia to the table and discuss it all together,” Firtash said. “People say I want to swap democracy for cheap gas – I want to have both. I would like to have European values. But let’s be honest, if we turn one way or the other, we lose a lot. We can’t be without Russia, because for us it’s a huge market. But we don’t want to lose Europe either. Why do we have to choose?”

• This article was amended on 27 June 2019. An earlier version incorrectly said Firtash was a former business partner of the former Trump campaign manager Paul Manafort. Representatives for Firtash say he turned down a business deal proposed by Manafort.