Pro-Russia separatists in eastern Ukraine plan to hold a vote on independence this weekend despite President Vladimir Putin's call to delay it.
The co-ordinating committee of the self-proclaimed 'Donetsk People's Republic' announced it would have a referendum as planned on Sunday, following a meeting.
But some people fear the vote in the regions of Donetsk and Luhansk could spark further violence between Ukrainian troops and the pro-Russia militants.
The separatists have already seized government buildings in about a dozen cities in the east of the country.
Russian leader Mr Putin wants the vote postponed so talks can take place with the Kiev government.
However, many in the east said the referendum was the only way to prevent war against what the rebels and Moscow call the "fascist" politicians in the capital.
President Putin wants the independence vote postponedHead of the rebel elections commission Denis Pushilin said the suggestion to put off the vote "came from a person who indeed cares for the people of the southeast" of Ukraine. "But we are the bullhorn of the people," he said.
The Russian stock market fell on the news and Kiev officials promised to continue with their "anti-terrorist campaign" to retake control of Donetsk and Luhansk regardless of the poll decision.
The European Union said the rebel vote has "no democratic legitimacy" and can "only further worsen the situation".
Mr Putin's comments appeared to be an attempt to try to defuse the row with the West over Ukraine.
The president also declared that Russia had pulled its troops away from the Ukrainian border.
Nato and the US said they had seen no signs of this.
Mr Putin also spoke more positively about the Ukrainian interim government's plan to hold a presidential election on May 25.
Pro-Russia activists stand guard during a rally in LuhanskHe called it a "step in the right direction," but reiterated Russia's view that there should be constitutional reforms beforehand.
The West has accused Russia of orchestrating violence in eastern Ukraine in order to justify a military intervention, something which Moscow has strenuously denied.
The European Union and United States have imposed a series of sanctions against Russian and Ukrainian individuals and companies.
Russia hit back on Thursday by expanding its list of American and Canadian individuals barred from Russia. The foreign ministry declined to name those affected.
It's defence ministry also warned that Ukraine had assembled 15,000 troops on its border with Russia.