Ukraine's nationalist Right Sector leader Oleksandr Muzychko aka Sashko Bily
Ukraine's nationalist Right Sector leader Oleksandr Muzychko aka Sashko Bily was killed during a raid. Police investigations show that he accidentally shot himself. YouTube

The Ukrainian far-right leader, who died during a shootout last month is now believed to have accidentally killed himself, according to police investigations.

Oleksandr Muzychko, mistakenly fired a gun on himself, when he was wrestling with the police during an encounter, the BBC reported.

According to reports, police had come to arrest him in the western city of Rivne, when he opened fire. As police chased and fought with him, two shots were fired by him. The first one barely scratched his skin, but the second went to his heart, killing him instantly.

Authorities had always maintained that Muzytchko aka Sashko Bily was killed by his own weapon.

He was the regional leader of Pravy Sektor (Right Sector), and a major player in Ukraine's protests. The group has not yet commented on the police report.

The far-right group had vowed to avenge Muzytchko's death, and a crowd of about 1,000 marched to the parliament building, smashing windows and demanding the resignation of the interior minister, Arsen Avakov.

"We will avenge ourselves on Arsen Avakov for the death of our brother. The shooting of Sashko Bily is a contract killing ordered by the minister," Roman Koval, a member of Pravy Sektor told a local internet newspaper Ukrayinska Pravda.

Pravy Sektor was reportedly instrumental in unseating pro-Moscow president Viktor Yanukovych, and has been considered a neo-Nazi organisation by Russia, according to AFP.

The group which helped dethrone the previous regime has now created problems for the new leaders.

Pravy members reportedly threatened minorities and Russian speakers, giving a bad name to the new government, which Russia already claims is 'fascist.'

Ukraine's new rulers are battling to stay in power in the face of pro-Russian protests spreading in the country following the Russian annexation of Crimea.

Pravy has its own political ambitions, and has formed a political party under the leadership of Dmytro Yarosh who will be contesting the Ukrainian presidential elections on 25 May.

Muzytchko was wanted in Russia in connection with the killing of 20 Russian soldiers, and for supporting Chechnya separatists.