Rival protests are expected in central Kiev, amid fears of possible clashes.
Activists and opposition parties are hoping hundreds of thousands of people will take part in a “Dignity Day” rally in the central Independence Square.
President Viktor Yanukovych’s supporters will gather in the nearby Mariinskyi Park.
Protests began last month after the president’s last-minute move to pull out of a landmark deal with the EU.
Viktor Yanukovych has said he fears the association and trade agreement will put at risk many enterprises dependent on trade with Russia.
The president – who says he eventually aims to sign the deal – has also admitted being under heavy pressure from Moscow, which wants Kiev to join a Russian-led customs union instead.
Several thousands pro-EU protesters remained overnight in Independence Square ahead of their rally, which is expected to start at 12:00 local time on Sunday.
Barricades around the perimeter of the main protest encampment in the heart of the capital have been strengthened following an attempt by special police to dismantle them earlier this week.
Opposition leaders have urged protesters to remain vigilant, fearing “provocateurs” could trigger clashes between rival demonstrators.
The opposition has also accused the authorities of bussing people into Kiev for the pro-government rally and providing them with money and food.
The authorities officially deny this, but a number of participants in the rally have said they were forced to take part.
The two rival camps held demonstrations close to each other on Saturday. There were no reports of any clashes.
President Viktor Yanukovych suspended his deputy security chief and Kiev’s mayor over the police violence against pro EU-protesters on November 30.
Prosecutors are investigating Volodymyr Syvkovych and Olexander Popov – alongside another two senior officials – on suspicion of abuse of office in the crackdown.
This has energized the pro-EU protesters, who are demanding that all those involved in the clampdown be sacked and punished. They also want the government to resign.
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