KIEV, Ukraine (AP) — Hundreds of thousands of Ukrainians rallied in the center of Kiev on Sunday in the biggest protest since 2004's pro-democracy Orange Revolution, denouncing President Viktor Yanukovych's decision to turn away from Europe and raising the stakes in a tense political standoff gripping this ex-Soviet republic.
An opposition leader said the protest had matched its billing as "The March of a Million." Video airing on local websites taken from high above the square showed streets jammed with crowds into the distance.
The Associated Press could not immediately verify Oleksandr Turchynov's count. But AP reporters on the ground estimate that more than 500,000 crammed into and around Kiev's central square, waving European Union flags and singing the national anthem.
As the government played hardball, threatening harsh measures against the demonstrators and arresting opposition activists, protests only gained steam.
"Yanukovych has lost legitimacy as president ... He is no longer the president of our state. He is a tyrant," jailed former Prime Minister Yulia Tymoshenko said in a letter to the crowd read by her daughter. "Don't give in, not a step back, don't give up, the future of Ukraine is in your hands."
The demonstrations erupted last month after Yanukovych shelved a long-planned treaty with the European Union to focus on ties with Russia. They were also galvanized by police violence and fears that Yanukovych was on the verge of bringing his country into a Russian-led economic alliance, which critics say could end Ukraine's sovereignty.
"It's not just a simple revolution," Oleh Tyahnybok, an opposition leader with the national Svoboda party, told the crowd in a fiery speech from a giant stage. "It's a revolution of dignity."
A solution to the crisis appeared elusive, with the government pretending not to notice the protests, and the opposition issuing contradictory statements on how to proceed next.
In her letter, Tymoshenko spoke against holding any talks with the government unless they entail early elections, even though her top ally Arseniy Yatsenyuk signaled the day before that talks were possible if Yanukovych fires his prime minister. Western diplomats have also been urging dialogue.
World boxing champion Vitali Klitschko, another top opposition leader, sided with Tymoshenko in calling for Yanukovych's ouster and early presidential elections, even though there is no legal possibility to impeach him and virtually no chance that he would resign on his own.
"We will fight and we are confident that we will win," Klitschko said.
But Yatsenyuk focused more on dismissing Prime Minsister Mykola Azarov, punishing the police who used force against demonstrators and freeing about a dozen opposition activists arrested since last Sunday's rally. He urged demonstrators to blockade the entire government district in Kiev, the capital, which houses the Cabinet, the presidential administration and the parliament.
"We are extending our demonstration. We are going to fight until victory. We will fight for what we believe in," Yatsenyuk told the crowd, which was drowning in a sea of flags.
A much smaller pro-government rally was held dangerously close to the opposition march. The two crowds were separated by police, but demonstrators then mingled openly in a nearby park and there were fears of clashes.
The protest in sub-zero December temperatures took place on Independence Square, known as the Maidan, in an echo of the Orange Revolution. Those protests annulled Yanukovych's fraud-tainted victory and ushered his pro-Western opponents to power.
"Ukraine is tired of Yanukovych, we need new rules, we need to completely change those in power," said protester Kostyantyn Meselyuk, 42. "Europe can help us."
The demonstrations began last month after Yanukovych shelved the signing of an agreement to deepen ties with the 28-nation European Union in order to focus on Russia, which worked aggressively to derail the EU deal.
During a huge demonstration a week ago, several hundred radical protesters hurled stones and attacked police as they tried to storm the presidential office, prompting a violent breakup by the authorities in which dozens were injured, including peaceful protesters, passers-by and journalists.
Maria Danilova contributed to this report.