The leader of ultranationalist group Right Sector, Dmytro Yarosh, talks, during his press statement, in Kiev, Ukraine, Tuesday, March 25, 2014. Yarosh lashed out at the killing of activist Oleksandr Muzychko, and said authorities responsible should be made to pay the price. "We cannot silently watch as the Interior Ministry carries out active antirevolutionary activities." Yarosh demanded the immediate resignation of Interior Minister Arsen Avakov. (AP Photo/Efrem Lukatsky)

The leader of ultranationalist group Right Sector, Dmytro Yarosh, talks, during his press statement, in Kiev, Ukraine, Tuesday, March 25, 2014. Yarosh lashed out at the killing of activist Oleksandr Muzychko, and said authorities responsible should be made to pay the price. "We cannot silently watch as the Interior Ministry carries out active antirevolutionary activities." Yarosh demanded the immediate resignation of Interior Minister Arsen Avakov. (AP Photo/Efrem Lukatsky)

The leader of ultranationalist group Right Sector, Dmytro Yarosh, centre, pauses, during his press statement, in Kiev, Ukraine, Tuesday, March 25, 2014. Yarosh lashed out at the killing of activist Oleksandr Muzychko, and said authorities responsible should be made to pay the price. "We cannot silently watch as the Interior Ministry carries out active antirevolutionary activities." Yarosh demanded the immediate resignation of Interior Minister Arsen Avakov. (AP Photo/Efrem Lukatsky)

The leader of ultranationalist group Right Sector, Dmytro Yarosh, talks, during his press statement, in Kiev, Ukraine, Tuesday, March 25, 2014. Yarosh lashed out at the killing of activist Oleksandr Muzychko, and said authorities responsible should be made to pay the price. "We cannot silently watch as the Interior Ministry carries out active antirevolutionary activities." Yarosh demanded the immediate resignation of Interior Minister Arsen Avakov. (AP Photo/Efrem Lukatsky)

Dmytro Yarosh, head of Ukrainian far-right nationalist organization Pravy Sektor (Right Sector), speaks to journalists during a press conference in Kiev on March 8, 2014. Ukraine's far-right Pravy Sektor movement on March 7 announced its leader Dmytro Yarosh would make a presidential bid in elections scheduled for May 25. The movement, which took a leading role in the deadly protests that unseated former president Viktor Yanukovych, will also become a political party. AFP PHOTO/ YURY KIRNICHNY

Dmytro Yarosh, head of Ukrainian far-right nationalist organization Pravy Sektor (Right Sector), smiles as he speaks to journalists during a press conference in Kiev on March 8, 2014. Ukraine's far-right Pravy Sektor movement on March 7 announced its leader Dmytro Yarosh would make a presidential bid in elections scheduled for May 25. The movement, which took a leading role in the deadly protests that unseated former president Viktor Yanukovych, will also become a political party. AFP PHOTO/ YURY KIRNICHNY

Dmytro Yarosh, head of Ukrainian far-right nationalist organization Pravy Sektor (Right Sector), speaks to journalists during a press conference in Kiev on March 8, 2014. Ukraine's far-right Pravy Sektor movement on March 7 announced its leader Dmytro Yarosh would make a presidential bid in elections scheduled for May 25. The movement, which took a leading role in the deadly protests that unseated former president Viktor Yanukovych, will also become a political party. AFP PHOTO/ YURY KIRNICHNY