Ukrainian government officials asked for volunteers on Tuesday to help quell pro-Russian rebellions in the eastern part of the country, according to the Washington Post.

The requests come less than three weeks before the May 25 elections and one day after approximately 30 pro-Russian militants and four Ukrainian soldiers were killed during a shootout in the city of Sloviansk. Dozens were reported injured on both sides. Approximately 800 armed Russian sympathizers had ambushed a Ukrainian force and lit fire to cars and surrounding buildings.

Pro-Russian gunmen guard an entrance of the Regional Prosecutor's Office building they seized on in Luhansk, one of the largest cities in eastern Ukraine, on April 30. Image: Alexander Zemlianichenko/Associated Press

One of the more prominent figures to call for a "volunteer army" was former Ukrainian Prime Minister Yulia Tymoshenko, who urged her countrymen to fight pro-Moscow militias because she felt the country's army and its security forces were unable to do so effectively.

Fighting in eastern Ukrainian cities has expanded over the past few weeks as pro-Russian separatists—who have aligned themselves with the Russian government in Moscow over the Ukrainian government in Kiev—have clashed with government forces in Ukraine who are trying to reclaim authority in the region.

Rebel militias have taken over around 20 government buildings in more than 10 eastern Ukrainian cities.

Russian President Vladimir Putin has said his government has an obligation to protect ethnic Russians, of which there are many in eastern Ukraine, a part of that country where many speak Russian as a first language.

Despite the natural Russian influence in eastern Ukraine, the United States government and others have accused Moscow of coaxing rebellion to create the illusion that Russian soldiers will have to invade to bring peace back to the region.

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Such an operation would be similar to what happened in Crimea, the peninsula to the south of Ukraine that Russia recently annexed. Pro-Russian separatists stoked rebellion there before Russian troops without insignia took over wide swaths of territory.

Acting Interior Minister Arsen Avakov, the highest-ranking security official in Ukraine, has said the Ukrainian government is willing to talk to leaders in the nation's east about giving them more autonomy.