KIEV, Ukraine (CBS) -- Thousands of Ukrainians chanted "Hero!" and sang the national anthem, as a coffin carrying a protester who was killed in last week's clashes with police was carried through the streets of the capital, underscoring the rising tensions in the country's two-month political crisis.
Mikhail Zhiznevsky, 25, was one of two protesters who died of gunshot wounds on Wednesday.
The opposition contends they were shot by police in an area where demonstrators had been throwing rocks and firebombs at riot police for several days. The government claims the two demonstrators were killed with hunting rifles, which they say police do not carry.
Meanwhile, protests against President Viktor Yanukovych continued to engulf the country, now spreading to central and eastern Ukraine, the leader's support base.
Nina Uvarov, 25, a student from Kiev wept as Zhiznevsky's body was carried out of St. Michael's Cathedral. "He could have been my fiancé, but he died defending my future so that I will live in a different Ukraine."
Zhiznevsky's body was being carried to the site of his death about 700 yards away, at barricades near the Ukrainian parliament. Prayers were also to be read at the nearby Independence Square in the center of the Ukrainian capital, where protesters have established a large tent camp and held demonstrations around the clock since early December. Sunday rallies in previous weeks have attracted especially large crowds, sometimes exceeding 100,000 people.
The protests began in late November after Yanukovych shelved a long-awaited agreement to deepen ties with the European Union, but they have been increasingly gripped by people seeking more radical action, even as moderate opposition leaders have pleaded for the violence to end.
A crowd late Saturday besieged a building, throwing fireworks, firebombs and rocks, near the protest tent camp where about 200 police were sheltering. By early Sunday morning a corridor was created, allowing police to leave.
Thousands of people were already in the square on Sunday afternoon, but opposition leaders may be betting that by not formally calling people together for a rally the event will be smaller.
The overnight outburst came soon after opposition leaders issued a defiant response to Yanukovych's offer to make Arseniy Yatsenyuk, one of their top figures, the country's prime minister. While not rejecting the offer outright, Yatsenyuk said more of the opposition's demands must be met, including Yanukovych's resignation. He vowed protests will continue.
About half of Ukraine's people favored deeper integration with the EU, according to polls, and many Ukrainians widely resent Russia's long influence over the country.
In the past week, demonstrators have seized government administration buildings in a score of cities in western Ukraine, where Yanukovych's support is weak and desire for European ties is strong.
Zhiznevsky was from Belarus, a neighboring ex-Soviet country where hardline President Alexander Lukashenko has jailed and harassed his opponents. Vladimir Neklyaev, a Belarusian opposition leader, came to Kiev to bid farewell to Zhiznevsky.
"Ukraine is showing Belarus an example of how one should fight for freedom," Neklyaev said. "I am sure that our countries have a common future in Europe, where neither Ukrainians nor Belarusians will die."
Despite an offer to release activists and stop more persecutions, the government continued a crackdown, with over 40 detained in the central city of Cherkasy after a protest, according to prosecutors.