KIEV, Jan. 17 (Xinhua) -- Ukrainian voters headed to polling stations on Sunday for the country's first presidential election since the 2004 "Orange Revolution."

    Incumbent President Viktor Yushchenko, Prime Minister Yulia Tymoshenko and opposition leader Viktor Yanukovich, a former prime minister, are among the 18 candidates vying for the former Soviet republic's top job.

    Some 36 million registered voters were expected to vote at 33,000 polling stations across the country and more than 3,000 international observers were monitoring the election, according to the Ukrainian Central Election Commission.

    Polls opened at 8:00 a.m. (0600 GMT) and will close at 8:00 p.m. (1800 GMT). Exit poll results are expected shortly after the closing of the polls. Official results will be published in 10 days.

    Pre-election opinion polls were indicating that no one would secure an outright victory by garnering over 50 percent of the vote. Yanukovich and Tymoshenko, who were leading the polls, are expected to compete in a run-off scheduled for Feb. 7.

    Yanukovich, who draws the bulk of his support from the Russian-speaking areas of the industrial east and the south, was on course to lead with 25 to32 percent of the vote.

    He has promised Ukrainians economic revival, new jobs, pay raises, judicial reforms and tax-free policies for small enterprises for five years.

    Tymoshenko trailed Yanukovich in pre-election polls by about 10percentage points. The former Yushchenko ally in the Orange Revolution, whose power base is in the west of the country, gave priority to a fair society and government efficiency, and pledged innovation-driven economic structure reform and improvement in people's welfare.

    Tymoshenko cast her ballot in the eastern industrial city of Dnipropetrovsk, her hometown. "Today's election is not only a presidential race but also an election for Ukraine's future for decades ahead," said Tymoshenko, dressed in a white coat.

    Tymoshenko's husband and their daughter accompanied her to the polling station. "This time our whole family arrived in the city where we were born and where we spent our youth. And today we are voting for the future of our Ukraine," she told reporters.

    Sergei Tigipko, another top contender, said he voted for Ukraine's democracy, economic reform and competitiveness as he cast his ballot in downtown Kiev, the capital city.

    "For me it is primarily a race between new and old, between changes and what we have now, between the country's modernization and the stagnation that we have seen in our country in the past five years," said Tigipko.

    Wealthy businessman Tigipko, a former economy minister, has made surprising gains against the two front-runners in a surge fueled by wide resentment of the nation's government and Tymoshenko.

    Yanukovich also voted in Kiev. "I have a feeling that Ukrainians hope for changes, and a new stage for the country will soon begin," he said.

    Asked about his foreign policy priorities if elected, Yanukovich said he will work with the West, Russia as well as other countries.

    Labeled as a pro-Russian politician, Yanukovich said he would seek a balanced, mutually beneficial and friendly foreign policy, in contrast to Yushchenko's active pursuit of NATO membership and hostility toward Moscow.

    Yushchenko, who swept to power in the Orange Revolution, said he hoped to win Sunday's election, which, he claimed, will demonstrate that Ukraine is a European country.

    "I have no doubt that Ukraine will again demonstrate that it is a European democratic country with a free nation, free people and free choice," Yushchenko told reporters after voting in Kiev.

    Asked what he would do if he is not to be re-elected, Yushchenko said: "I will be."

    Pre-election opinion polls showed that the West-leaning president had little chance of winning a second term in office.

    With Yushchenko's departure from power, analysts forecast a slowdown in Ukraine's bid for NATO membership and a thaw in the Ukraine-Russia ties.

    However, as the country is struggling with an economic downturn, Kiev is hungry for assistance and support from the West.

    Therefore, it is generally believed that a new president will cement ties with Russia and at the same time maintain cooperation with the West.

    Vladimir Shapoval, chairman of the Central Election Commission, told a press conference earlier in the day that there had been no serious incidents in the presidential poll. "The election are being held smoothly, and there will be no disruption."

    Under the constitution, the president is elected for a five-year term, which can be renewed once. The president-elected president shall assume office no later than 30 days after the official publication of the final results.

    This is the fifth presidential election in Ukraine since the collapse of the Soviet Union in 1991.