Protests in Ukraine are spreading further outside Kiev, with reports of unrest in the east, north and south.
Activists besieged government buildings and in some cities clashed with riot police. In the capital, protesters took over the justice ministry.
The fresh unrest comes after opposition leader Arseniy Yatsenyuk rejected President Viktor Yanukovych's offer to appoint him prime minister.
He said key demands must be met, including new elections.
As well as his offer to Mr Yatsenyuk, he suggested another opposition figure, former boxer Vitali Klitschko, take the post of deputy prime minister following talks on Saturday.
The BBC's David Stern, in Kiev, says the opposition - confident in its position - appears to have taken Mr Yanukovych's offer of concessions as a sign of weakness, and is forging ahead with the campaign to unseat him.
The demonstrations began in November after Ukraine decided not to sign an accord on more co-operation with the EU.
Instead, the government opted to deepen ties with neighbouring Russia.
On Friday protesters seized several government buildings in cities outside Kiev, particularly in the west, which has traditionally favoured closer ties with Europe, including in the cities of Chernivtsi, Ivano-Frankivsk, Lutsk and Lviv.
On Saturday the protests spread to cities further east, including Vinnytsya, south-west of Kiev.
Reports now suggest unrest is spreading further into the country's east, which has traditionally had closer ties with Russia and is Mr Yanukovych's support base:
- In the north-eastern city of Sumy, protesters occupied the city's council building and an MP for the opposition Fatherland party has assumed the leadership of the council, reports Ukraine's Unian news agency
- Several thousand protesters tried to storm the state regional administration building in south-eastern Zaporizhzhya, with police using tear gas and smoke grenades against the crowd and eventually dispersing them, reports said
- Some 2,000 people gathered for a people's assembly in Cherkasy, south-east of Kiev, said Unian. More than 40 people were reportedly detained there after a protest.
- Activists in Chernihiv, north of Kiev, set up barricades outside a regional administration building which they attempted to storm on Saturday, Unian reported
- In Dnipropetrovsk, eastern Ukraine, there were clashes as protesters descended on the regional administration buildings; 14 protesters were arrested, said Interfax-Ukraine news agency
- Protesters in Odessa, to the south, also gathered at the regional office
- In the north-eastern city of Kharkiv, a group of young men armed with baseball bats attacked anti-government protesters who had gathered for a rally, Interfax-Ukraine news agency reported
In total, municipal buildings have reportedly been seized by protesters in up to 10 cities outside Kiev - unrest on a scale which commentators say is unprecedented in post-Soviet Ukraine.
Meanwhile, in central Kiev, activists have seized the justice ministry building and are calling for others to join them.
Protesters told the BBC there were no guards and they simply smashed their way in through the window.
"We don't need this justice for sale anymore," a masked protester said.
Earlier, thousands mourned a protester who was killed last week.
Crowds chanted "Hero!" as the open coffin of Mikhail Zhiznevsky, 25, was carried through the streets of the capital.
The opposition is demanding that a free trade agreement with the European Union be signed and political prisoners be freed, including former Prime Minister Yulia Tymoshenko.
They are also demanding the repeal of recently introduced laws restricting public protest, and early presidential elections. A vote is not due until 2015.
The crisis in Ukraine escalated with the deaths of four activists in recent days.
Although the protest movement - the EuroMaidan - is largely peaceful, a hardcore of radicals have been fighting battles with police away from the main protest camp in Maidan, or Independence Square.