Dmytro Firtash, the 48 Ukrainian gas industry oligarch who was arrested in Austria last week, has hit back at authorities by claiming his incarceration is "politically motivated" and "without foundation."
In a statement sent to IBTimes UK by his legal representation, Firtash, also known as Dmitry, said "I believe strongly that the motivation was purely political" and that "my detention will seriously threaten many Ukrainian jobs and destroy my business."
Last week, Austrian prosecutors seized Firtash under the Federal Criminal Agency's (FCA) orders.
He has been under investigation by the US Federal Bureau of Investigation (FBI) since 2006.
"Based on years of investigations by the US FBI and an arrest warrant issued by a US federal district court, Vienna prosecutors issued a national order to detain the businessman," said the FCA in a public statement.
The agency added that he was arrested on the suspected violation of bribery laws and forming a criminal organisation.
Firtash is one of the top ten richest men in Ukraine and is tipped to be worth around $1bn (£599m, €717m) and is the co-owner of RosUkrEnergo, which controls most of Ukraine's lucrative titanium business.
Firtash acquired chemicals plant Stirol in Donetsk in the aftermath of Yulia Tymoshenko losing out to Viktor Yanukovych in the 2010 presidential election.
During the same year, he won an international arbitration court ruling, which forced Ukraine's state gas company to hand over around $3bn of gas.
Over the last three years, dissidents have suggested that Yanukovych's inner circle handed Firtash more influence over the country than Ukraine's richest man, Rinat Akmetov.
Famously, in a Wikileaks cable dated December 2008, Firtash confirmed to then US Ambassador to Ukraine William Taylor, that he once had ties with alleged Russian mafia boss Semyon Mogilevich.
Taylor quoted Firtash in the cable saying that "he needed, and received, permission from Mogilevich when he established various businesses, but he denied any close relationship to him."
Firtash has always denied any links to the mafia.
His full statement:
"The reason for my detention in Vienna last week was without foundation and I believe strongly that the motivation was purely political.
"The future of Ukraine is at a delicate and defining point. I have worked behind the scenes for many months with a variety of political and religious leaders to try and help my nation.
"As the largest private sector employer in Crimea, my absence from Ukraine, I believe, will further destabilise a political process that involves many people working around the clock to achieve peace.
"The President of the United States of America, Barack Obama, has said that the United States will impose economic sanctions on Russia so as a Ukrainian, why I was detained is as bewildering as it was unfair.
"My detention will seriously threaten many Ukrainian jobs and destroy my business.
"But this unjust action by the United States cuts much deeper and, if their legal moves continue, further harm and anguish will be caused among my fellow Ukrainian citizens."