MOSCOW, March 13 (RAPSI) - Ukrainian gas mogul Dmytro Firtash has been arrested in Vienna, Reuters reported Thursday citing sources in the Austrian government. 

Reuters reported that the Federal Criminal Office identified the detainee simply as Dmitry F., and said that he was being investigated by the US Federal Bureau of Investigation (FBI). 

Firtash, co-owner of Ukrainian gas giant RosUkrEnergo, made headlines between 2011 and 2013 as a result of the lawsuit filed against him and his company in the US by former Ukrainian prime minister Yulia Tymoshenko. 

The lawsuit against Firtash and RosUkrEnergo was filed in April 2011 on behalf of Tymoshenko, the people of Ukraine and a group of opposition politicians kept under detention or prosecuted by the investigative authorities. The plaintiffs claimed that influential circles in Ukraine have established a complex money laundering scheme abroad and a scheme to bribe Ukrainian officials. 

Tymoshenko's lawsuit centered on a 2009 gas conflict after negotiations stalled between Kiev and Moscow on gas supplies to Ukraine and gas transit to Europe. In the absence of a supply contract, Russia stopped supplying gas to Ukraine and then to Europe as Kiev started siphoning off gas for its own needs. 

Russia's Gazprom and Ukraine's Naftogaz refused mediators' services, particularly RosUkrEnergo, which eventually contested the ownership of 11 billion cubic meters of gas in the Arbitration Institute of the Stockholm Chamber of Commerce. 

The case was dismissed without prejudice. 

In October 2011, Tymoshenko was sentenced to seven years in prison for abuse of power based on a 2009 gas contract that she signed with Russia.
In late March, a second case bringing further charges against Tymoshenko was filed with Kharkiv's Kievsky District Court. The case deals with her activity at United Energy Systems. She has also been accused of misappropriating funds. 

On February 22, Ukraine's parliament voted to release Tymoshenko from prison. The news followed closely on the heels of the adoption on February 21 by the parliament of sweeping amendments to the Criminal Code which carried the potential of clearing the way for her release.