Hundreds of Ukrainians rallied in the capital of Kiev on Tuesday in support of the ultranationalist Right Sector group after a series of tense standoffs with government forces in recent weeks. The radical group played a major role during protests in Kiev last year and helped topple the regime of former president Viktor Yanukovych.

The far-right group was involved in a shootout with police forces near the western city of Mukacheve that killed two of its members. The men were reportedly killed after Right Sector members fired on police officials. However, the group insists that its members were trying to crack down on a police-run smuggling business in the region. After a shootout with guns and grenades, a group of Right Sector members remain camped in the woods near Mukacheve, and have reportedly refused to disarm and surrender.

Human rights groups and local authorities have also accused the Right Sector of illegally carrying weapons, kidnapping and torturing civilians, and violently pursuing their goals.

Right Sector leader Dmytro Yarosh also called Tuesday for a referendum to impeach the government of President Petro Poroshenko. He demanded that volunteer battalions be officially recognized and that they be given the right to bear arms, and the introduction of a martial law to help fight the conflict raging in the country's east. Yarosh also reportedly accused the new government that replaced Yanukovych's regime of doing little, except "changing names."

"We are an organized revolutionary force that is opening the new phase of the Ukrainian revolution," he told the assembled supporters, according to the Associated Press.

Several Ukrainian oligarchs and political groups have private military wings, which have become deeply controversial amid allegations of human rights abuses and standoffs with government forces. In March, a "pocket army" funded by Ukrainian billionaire Igor Kolomoisky occupied state energy firms and held a tense standoff with government forces, prompting a crackdown on unofficial military groups.

However, hundreds of men reportedly still carry weapons without authorization in Ukraine's conflict-ridden east.

Yarosh also said that the government was unjustly cracking down on the group and hunting its members instead of focusing on the ongoing conflict. "Our guys were spilling their blood (in the east) but now they are being punished behind the lines," he reportedly said.

Yarosh reportedly indicated that the Right Sector members near Mukacheve were not under his command and that he was unsure how many men were still involved in the standoff. He also dismissed reports that Right Sector militants were using weapons, which were meant to fight rebels, elsewhere in the country.

Two of Ukraine's most powerful volunteer militias, the Azov and Donbass battalions, also voiced their support of the Right Sector and called for a nonviolent resolution to the Mukacheve standoff, the Telegraph reported.