Ukrainian Prime Minister Yulia Tymoshenko said on Saturday that she had evidence of fraud in the Feb. 7 presidential runoff, and would challenge the result in court.

Preliminary results from the Ukraine Central Election Commission showed that Tymoshenko was defeated by opposition leader Viktor Yanukovych by just 3.5 percentage points.

Tymoshenko said more than 1 million votes had been falsified or miscounted, and irregularities were particularly rampant in certain Russian-speaking areas.

"I want to clearly state: Yanukovych is not our president. Whatever happens in the future, he will never become the legitimately elected president of Ukraine," she said in a televised broadcast to the nation.

"I have made the only decision I can make -- to challenge the results in court," Tymoshenko said. "Not going to the courts today would mean leaving Ukraine to criminals without a fight."

Observers from the Organization for Security and Cooperation in Europe (OSCE) have declared the elections "professional, transparent and honest" in a joint statement with other international observers.

Some foreign leaders including U.S. President Barack Obama and NATO Secretary-General Anders Fogh Rasmussen have already congratulated Yanukovych on his election win.

A Ukrainian electoral official told Xinhua earlier this week that Yanukovych's victory was "unassailable," though it was won by a small margin.

Volodymyr Fesenko, director of the Penta Center of Applied Political Studies, said Tymoshenko's attempt to challenge the election results in court was meaningless and would not lead to a revote like the one at the end of 2004 during the "Orange Revolution."

Analysts have ruled out the possibility of an outbreak of street protests, citing decreasing revolutionary fervor among the population, who have benefited little from the "Orange Revolution."

Instead, they predict a smooth transition of power from incumbent president Viktor Yushchenko to Yanukovych.