Demonstrators were still occupying regional administration buildings in Lviv and other regions across the pro-EU west of Ukraine that they have seized in a major blow for President Viktor Yanukovych.
But in a new development, protesters were seeking to seize buildings in regions north and east of the capital Kiev, in a sign the protest mood was spreading across the country.
Protesters were storming the regional administration in the region of Poltava east of Kiev, Ukrainian media reports said.
Demonstrators had earlier seized control of the regional administration building in the region of Vinnytsia just to the west of Kiev, undeterred by stun grenades used by riot police.
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Governors of Ukrainian regions are appointed by Yanukovych and have now become targets of protesters seeking to bring about change not just in Kiev but across the country.
As well as Lviv, protesters are already controlling administration buildings in the western regions of Ternopil, Rivne, Khmelnitsky, Lutsk, Ivano-Frankivsk and Chernivtsi.
Yanukovych has always been hugely unpopular in western Ukraine, which overwhelmingly favours integration with the European Union and a slackening of ties with Russia.
Ukraine has long been split between the nationalist and Ukrainian-speaking west and far more Russophile east. The south, in particular Crimea, also tends to favour Yanukovych.
A large number of the protesters currently massing against Yanukovych in Kiev are not from the capital but have travelled in huge numbers from western Ukraine.