About 1,000 protesters blocked off the Ukrainian government's main headquarters on Monday and surrounding streets, preventing employees getting to work, in further protests at Kiev's policy U-turn away from integration with Europe.
In response to an opposition call for a nationwide strike over President Viktor Yanukovich's policy switch back towards Russia, protesters blocked the main approach road to the government building with trash bins, metal containers and even flower pots.
"Employees can not get into the building. Negotiations are going on with protesters to allow employees in," a spokesman for Prime Minister Mykola Azarov said. He added that Azarov had not yet arrived for work.
Protesters focused their attention on the government building after an opposition-led rally of about 350,000 people in the capital on Sunday, marred by violent clashes between police and protesters.
There was no immediate word from Yanukovich who is due to leave on an official visit to China on Tuesday. His press service said employees at his administration were working normally but it declined to say where he himself was.
Opposition leaders are demanding the resignation of Yanukovich and the government after he backed away from signing a landmark trade deal with the European Union, following years of careful preparation, and switched trade policy back towards Russia, Ukraine's former Soviet master.
There were violent clashes on Sunday near the main presidential administration building - Yanukovich's seat of power - with riot police using tear gas, stun grenades and batons to disperse crowds. Police later clashed with a group of masked protesters trying to pull down a monument to Soviet state founder Vladimir Lenin.
The opposition has called a nationwide strike from Monday though it was not immediately clear what support this was receiving in state concerns or private businesses across the country.
The National Bank, which is close to the government building, was working normally, but city hall was still occupied by protesters and its employees were told to stay at home.
Former interior minister Yuri Lutsenko, now an opposition figure, said: "What is happening now around the government building is a strike."
Alexei Ostrovsky, 36, who works in advertising, said: "I decided I have to be here. I think my bosses will understand that and don't fire me. Annoyingly my company is still working. But I understand them, some cannot allow themselves to strike - they have to feed their families."
Oksana, 22, cafe worker, said she sympathised with those who had gone out onto the streets to protest, but she needed the money and had to go to work.
A government employee who tried to enter the building said:
"We were told to go back home and await further instructions. We simply could not get to work. All the doors are blocked,"
Kiev's main throughfare and approach roads to its main Independence Square - focal point of Sunday's rally and the centre of the "Orange Revolution" protests nine years ago - were closed to traffic.
Protesters, who were chased from the square by riot police early on Saturday, had re-established themselves there in a makeshift encampment.