Profile: Ukrainian oligarch Dmytro Firtash
One of Ukraine's richest men, Dmytro Firtash made his fortune in the Central and Eastern European chemical and energy industry, emerging as a middleman in the trading of Central Asian gas after the collapse of the Soviet Union.
The gas tycoon's business interests centre on his Group DF (Group Dmytro Firtash) - one of the biggest players in the European energy market - with branches in many countries including Austria, Germany, Switzerland, Tajikistan and Ukraine. The 49 year old also owns one of Ukraine's most-watched television channels, Inter TV.
The self-made billionaire is said to come from a humble background in western Ukraine's Ternopil region and to have worked as a fireman before he began to build his business empire in the late 1980s. By 2012, Group DF was estimated to have an annual turnover of $6bn (£3.5bn; 4.3bn euros).
By 2009, Mr Firtash's role as an intermediary in the East-West gas trade was attracting the hostile attention of Ukraine's then Prime Minster Yulia Tymoshenko, who campaigned to have his company excluded from negotiations over the gas contract between Ukraine and Russia.
However, he succeeded in winning other powerful allies in the Ukrainian leadership, and exercised considerable influence on Ukrainian economic policy, especially during the presidency of Viktor Yanukovych.
Mr Firtash was regarded as one of Mr Yanukovych's main backers.
Two days before the president was ousted, with Kiev witnessing its bloodiest day since the pro-European protests had begun, he called for a peaceful resolution of the crisis, warning against "radical actions, no matter who commits them".
Weeks later he praised political efforts in Kiev aimed at restoring democratic stability to Ukraine.
Mr Firtash was detained in March in the Austrian capital Vienna after an arrest warrant was issued by the US authorities.
Austrian police said the arrest was not related to political events in Ukraine, but was made on the basis of a long-running investigation by the FBI into the tycoon's business activities.
He was subsequently released on bail and is currently awaiting extradition to the United States, where he is wanted on suspicion of corruption and forming a criminal organisation.
Mr Firtash rejects the allegations, saying that they are politically motivated and describing himself on his company website as a victim of the struggle between "the two largest and most influential geopolitical centres of the present day".