Incumbent Belarusian President Alexander Lukashenko secured a sixth term with 80.23 percent of the vote at the country's presidential election, the Central Election Commission announced, citing preliminary results on Monday. 

Svetlana Tikhanouskaya, a former English teacher who emerged as Lukashenko's main rival at the elections on Sunday, won 9.9 percent of the vote, the election commission said.

Lukashenko, 65, had a surprise rival in Tikhanouskaya, who entered the race after her husband, an anti-government blogger who intended to run, was jailed.

Her rallies drew large crowds and human rights groups say more than 1,300 people had been detained in a widening crackdown.

Polling stations in Minsk saw long lines gather hours before voting finished, AFP reported.

Election officials had warned they could restrict access to polling stations and Central Election Commission chief Lidia Yermoshina described the queues as "real sabotage, an organised provocation."

Security was tight in Belarus for the election, with police deployed across Minsk and special forces at checkpoints. 

Big queues had also formed at Belarusian embassies abroad, including in Moscow where hundreds were lined up outside the embassy only two hours before voting was due to end at 20:00 local time (17:00 GMT).

Belarus ramped up security measures on election day with police carrying machine-guns checking vehicles entering Minsk. There was a heightened police presence in the city and government buildings were cordoned off by police.

Prosecutor-General Alexander Konyuk urged voters to be "reasonable" and not take part in unsanctioned protests, Belta state news agency reported.

In comments broadcast on television, Lukashenko, who had earlier warned that his opponents wanted to stir up unrest, said: "No one will let anything get out of control. Nothing will get out of control, I guarantee you."

Tikhanovskaya, who joined forces for her campaign with the wife of one barred opposition chief and the campaign manager of another, said she would not call on her supporters to protest after the vote.

At the same time she asked police not to obey "criminal orders."

On Saturday, authorities arrested Tikhanovskaya's campaign manager and briefly detained one of her two top allies.

Tikhanovskaya was by far the strongest of Lukashenko's four rivals in opinion polls.

Independent observer group Right of Choice said that at least 28 of its observers had been detained and election officials barred others from entering polling stations.

Ahead of the vote Lukashenko warned that dissent would not be tolerated and that he would not give up his "beloved" Belarus.

"We will not give the country to you," he warned his opponents as he addressed the nation this week.

Lukashenko has sought to galvanise support by warning of outside threats and raising the spectre of violent mobs.

Belarus has detained more than 30 Russians Lukashenko said were mercenaries allegedly sent to the country to destabilise the vote.

The detentions sparked a political crisis with ally Russia, with Moscow urging the men's release and President Vladimir Putin telling Lukashenko that he wants Belarus to stay "stable."

Lukashenko has retained close ties to Moscow, though he has played Russia and the West off against each other.

France, Germany and Poland have urged Lukashenko to ensure a "free and fair" election and allow "independent surveillance of the vote by local observers".

But this time Minsk has not invited observers from the European OSCE observer group for the first time since 2001.