MINSK, March 19 (Xinhua) -- Belarus' incumbent President Alexander Lukashenko was taking a clear lead in exit polls against three other contenders in the presidential election as polls closed Sunday night.

    An exit poll, conducted by Belarus' Committee of Youth Organizations, gave Lukashenko 80 percent of the vote. The other three candidates got somewhere between 4-6 percent respectively. Preliminary results are expected late Sunday night or early Monday morning.

    Lukashenko, who is seeking re-election to a third term, is facing independent candidate Alexander Milinkevich, who is supported by the opposition, Liberal Democratic Party leader Sergei Gaidukevich and Social Democratic Party leader Alexander Kozulin.

    To avoid a run-off, a candidate must secure no less than 50 percent of the vote. Lidia Yermoshina, chairwoman of the Central Election Commission, dismissed a run-off as unneeded.

    Polling stations across the country, which lies between Russia and Poland, closed at 1800 GMT.

    Shortly afterwards, thousands of opposition supporters gathered on Minsk's main square for a rally. Police stood watching nearby. Earlier, despite a government ban on election-day rallies, Milinkevich had called for a peaceful gathering after polls closed.

    Earlier, Lukashenko said the authorities would react adequately to any moves by the opposition on voting day.

    "We'll respond appropriately to such moves, depending on how the situation develops," Lukashenko said, quoted by the Interfax news agency.

    A voter turnout of at least 50 percent is required for the election to be valid in Belarus, where about 7 million people were eligible to vote. Officials declared the vote valid several hours into polling.

    The Central Election Commission put the turnout at 92.6 percent at the end of voting, Interfax said.

    More than 1,200 international observers visited polling stations to monitor the election. The Organization for Security and Cooperation in Europe (OSCE) and the Commonwealth of Independent States (CIS) have sent the largest groups of election observers.

    Both the OSCE and CBS are expected to announce their assessment of the Belarus vote Monday afternoon. Enditem