Several hundred protesters have blocked entrances to the main headquarters of the Ukrainian government. They have also gathered outside of other key buildings and thousands have returned to Kyiv's main square.
On Monday, demonstrators gathered outside the Cabinet building in Kyiv prevented government staff from entering their offices.
"We were told to go back home and await further instructions," one Ukrainian government employee told the Reuters news agency. "We simply could not get to work. All the doors are blocked."
The blockade appeared to be part of a general strike called by the opposition over President Yanukovych's decision last week not to sign a deal that would have strengthened political and trade links with the European Union.
Several thousand protesters also returned to central Kyiv’s independence square on Monday, where a few hundred had spent the night in a tent camp. Others gathered outside of the capital’s city hall and a labor union building.
Protesters involved in Monday's demonstrations called on Prime Minister Nikolai Azarov and his Cabinet to step down.
Opposition leader Arseni Yatsenyuk said the resignation of Azarov, a close ally of the president, would be an important "first step."
This followed a mass demonstration on Sunday in which tens of thousands of protesters took to the streets of Kyiv in the Ukrainian capital’s largest public rally since the 2004 pro-democracy "Orange Revolution." Estimates of how many people took part in the protest varied widely, with some putting the number of demonstrators as low as 100,000, but others reporting several times that figure had taken part.
Protests turned violent in several parts of the city. Authorities reported that at least 150 people had been injured over the course of the weekend. Later, heavyweight boxing champion-turned-opposition-politician Vitali Klitschko called for a renewed push to bring down Yanukovych's government.
The protest movement picked up steam after the EU summit in Vilnius last Friday, where Yanukovych had originally been expected to sign an association agreement with the 28-member bloc. Instead he rejected the pact at the last minute, saying his country first needed an economic aid package from the West. He also described an EU offer of 600 million euros ($800 million) in aid as "humiliating." At the same time, though, he said Ukraine still intended to sign the deal in the near future.
The unrest in Ukraine has raised concerns in the European Union in particular. Speaking to reporters in Berlin on Monday, European Commission President Jose Manuel Barroso said the EU was looking on with great concern. He also said the protests were a sign that many Ukrainian people see their futures in Europe.
Outgoing German Foreign Minister Guido Westerwelle expressed a similar sentiment.
"The demonstrations are an impressive commitment to Europe by hundreds of thousands of people in Ukraine," Westerwelle said in a statement. "They show that the heart of the Ukrainian people beats in a European way."
Chancellor Angela Merkel, meanwhile, called on President Yanukovych to "do everything to safeguard free speech and the right to peaceful demonstration."
pfd/msh (AP, AFP, Reuters, dpa)