(CNN) -- Exit polls showed former Ukraine Prime Minister Viktor Yanukovich as the victor over current populist Prime Minister Yulia Tymoshenko in the runoff of the nation's presidential elections.
Oleksandr Turchinov, head of Tymoshenko's campaign, said it was too early to draw conclusions about the election results, and called the election a dirty one.
"I ask everyone who can hear me now to fight for every protocol and every act, to fight for every voice," Tymoshenko said Sunday after the exit polls were released. "Every voice can decide the future of the country."
The two politicians have fought a bitter battle. Tymoshenko, the underdog, had vowed to call her supporters to the streets if voting appeared fraudulent. Each side has accused the other of electoral fraud.
"If they succeed in perverting the election results through large-scale uncontrolled falsifications, then the legitimacy of that president will not be recognized by Ukraine or by the international community," Tymoshenko said.
Six exit polls were conducted. All of them showed Yanukovich leading Tymoshenko by at least three percentage points. The margin of error ranged from 0.8 to 1 percent.
Yanukovich polled 10 percentage points ahead of Tymoshenko in the first round of voting on January 17.
Meanwhile, Yanukovich's Party of Regions said it hoped Tymoshenko would concede defeat. The party's deputy head, Boris Kolesnokov, said Yanukovich led by more than 1 million votes.
"It was a difficult way we passed," Yanukovich said. "We offered changes and the people supported us. ... We made the first step towards uniting the country."
He said he wants to have policies "that would receive the trust of the whole Ukraine," including those who supported Tymoshenko or other candidates.
Tymoshenko said her team would be conducting a parallel vote count.
"If anybody announces any results or celebrates victory before the official vote count, this would be a manipulation," she said.
Preliminary estimates showed the turnout was about 69 percent.
Yanukovich has strong links to Russia, but a checkered election history.
In 2004, he was declared the winner of that year's presidential elections before the ballot's legitimacy was questioned and he was accused of stealing the race.
"The country remembers times when there were presidents announced, they received congratulations and then things changed," Tymoshenko warned Sunday, referring to the 2004 race.
A pro-Western uprising, known as the Orange Revolution, followed. Yanukovich's win was annulled.
The revolution put the current president, Victor Yuschenko, in power. He ran for a second term this year but, blamed for Ukraine's faltering economy, he did not make the runoff.
The Orange Revolution also swept Tymoshenko to power. She is campaigning for the top job vowing to lead Ukraine into the European Union and NATO.
"People are bored with her lies, hazardous policies and inability to rule the government effectively," Yanukovich said of his rival. "That's why the election will pass and she will leave very soon. People want this very much and are waiting for it."
CNN's Matthew Chance and journalist Victoria Butenko contributed to this report.