Polls opened at 8:00 a.m. (0700 UTC) and were to close at 8:00 p.m. (1900 UTC). Turnout passed the minimum 50 percent requirement for the polling to be declared valid within three hours, officials said.

"Already more than 50 percent of people registered on voter
lists have taken part," Nikolai Lozovik, deputy chairman of the central electoral commission, said on state television.

Lukashenko, who has ruled Belarus for 12 years, is widely expected to defeat his three opponents, winning a third term as leader of the ex-Soviet republic of 10 million people.

However, the main opposition candidate, Alexander Milinkevich, accuses Lukashenko of planning "total falsification" in the wake of a campaign that saw the opposition almost entirely denied media access and hundreds of activists detained.

Milinkevich, a 58-year-old physicist, repeated his call for a peaceful demonstration in central Minsk after polls close, despite repeated warnings from the authorities.

"I've invited those who are for change in our country to go to the square," he said after casting his vote in the capital. "If there are provocations, the responsibility will be with the authorities. We are peaceful."

The opposition appears to have little chance of mirroring the recent people-power revolutions that swept away entrenched regimes in Georgia, Kyrgyzstan and Ukraine after rigged elections.

Both opposition candidates complained Sunday that polling was being manipulated in favor of Lukashenko. Milinkevich said his activists were not being allowed to observe voting in polling stations. "They chase them out," he told journalists.

He also described as "a major violation" the frequent broadcast on state television of exit polls by pro-government institutes, showing Lukashenko to be cruising to crushing victory. Such polls "put pressure on voters on election day," he said.

Milinkevich accused authorities of "frightening people" through frequent statements indicating that any protest against the election results will result in bloodshed.

Another opposition candidate, Alexander Kozulin, said the result would be fixed. "We know an order has been given for Lukashenko to get 80 percent.... If this is confirmed, we will ask for a recount. Lukashenko can only keep power by force."

Demonstrations against regime to be "crushed"

Lukashenko, 51, has vowed to crush any demonstration, warning that authorities will "break the neck immediately -- like a duckling's." His KGB security service claims protestors are part of a Western-backed coup plot and could be executed or imprisoned for life as "terrorists."

On Saturday, many mobile phone subscribers in Belarus received an anonymous text message warning of "bloodshed" in Minsk and urging them to "watch out for life and health."

The confrontation in Belarus, sandwiched between the European Union and Russia, is also part of a battle for influence between the West and Moscow in the ex-Soviet territories.

US President George W. Bush has described Belarus as "the last dictatorship in Europe" and Western powers accuse Lukashenko of rigging Sunday's vote by stifling independent media, arresting activists and manipulating the electoral apparatus.

However, Moscow has warned the West not to meddle. Russia supports Belarus' growing economy with cheap energy supplies and the two countries are also in continuing talks on forming a "union state."

Two-term limit abandoned leaving president free to reign

Sunday's vote is a landmark for Lukashenko, as it follows the abolition of a two-term limit on holding the presidency at a controversial referendum in 2004. He enjoys support in large segments of Belarusian society for ensuring that pensions are paid on time and maintaining economic stability.

However, he also has the benefit of a powerful propaganda machine that was in full swing on election morning, with state television airing dozens of interviews with experts and ordinary people praising the fairness of the election system and success of Lukashenko's rule.

The central electoral commission chairwoman, Lidiya Yermoshina, told state television: "There have been no complaints from voters, only congratulatory telegrams."

The two other candidates taking part in the election are opposition leader Alexander Kozulin of the Social Democratic party and Liberal Democratic leader Sergei Gaidukevich, regarded as a mild critic of Lukashenko.

Opposition candidates restricted in campaigning

But, like Milinkevich, they have been allowed just one hour of television air time each in the whole election campaign, and were not expected to garner significant numbers of votes.

One voter, Yelena Lisenkova, 76, praised Lukashenko for "getting rid of all the drunks who didn't want to work."

"We need to get rid of the opposition so they don't organize riots, and don't interfere in our state," she said after casting her ballot in Minsk.

However, another voter, who said he was too scared to give his name, told reporters he and his family were voting for Milinkevich. "All normal-thinking, hopeful people are voting for him. People are tired of living in the past."

To avoid a run-off vote in Belarus, a candidate must win at least 50 percent of votes cast. At least half of the approximately seven million registered voters must take part for the election to be valid. The presidential term in office is five years.

Banned observers stage protests on border

Observers who were barred entry to Belarus for the presidential elections took part in a protest at Lithuania's border with Belarus, one of the organizers of the action said.

Some 80 Lithuanians, Poles and Scandinavians rallied at Medininkai border post for some two hours starting at midday, Tomas Tomilinas, a board member of the non-governmental organization, United Centre of Initiative for Belarus, told reporters.

"We came here to express our solidarity with the Belarus people who seek freedom," Rasa Rastauskiene, one of six Lithuanian lawmakers who this week were refused visas by the Belarus authorities, said.

"We do not want Belarus to be separated from Europe. The Belarus nation belongs to Europe and the Lukashenko regime is lowering a new iron curtain between Belarus and the European Union," Rastauskiene added.

All six Lithuanian legislators who this week were barred entry to Belarus took part in the protest, as did four members of Scandinavian non-government organization Silba, who were expelled from Belarus this week for alleged "illegal activities."

Tomilinas said similar actions also took place in Poland and Ukraine.