The 65-year-old has ruled over the ex-Soviet country wedged between Russia and Europe with an authoritarian grip for 26 years and has cracked down on the country's emboldened opposition in the lead-up to Sunday's election.

During a televised address to the nation, Lukashenko slammed what he said were attempts by his opponents to organise "a massacre" in the capital Minsk, claiming his critics were being backed by "billion-dollar resources" to incite unrest.

"Will Belarus survive? Will it survive this hybrid war?" he asked, sweating profusely and repeatedly mopping his brow.

"We will not give the country to you. Independence is expensive, but it is worth it," he said, flanked by large Belarusian flags in an auditorium packed with government officials, church leaders and uniformed military personnel.

The former collective farm director, who is Europe's longest-serving non-royal national leader, is seeking a sixth term in the upcoming ballot after barring his main rivals from contesting the vote and jailing some of them.

Last week the Belarusian security service, the KGB, arrested 33 Russian "militants" that the authorities said were plotting mass riots with the opposition.

Lukashenko said that on Tuesday he had received information about "another unit sent to the south" and added that Moscow should stop "lying" and interfering in his country's affairs.

"Do not blow up the situation or things will go up in flames and will be felt even in Vladivostok," he said, referring to Russia's Pacific port.

Minsk says the men detained last week are members of the Wagner private military company that promotes Moscow's interests in Syria, Libya and Ukraine and is reportedly controlled by a close ally of Russian President Vladimir Putin.

After Lukashenko's address the defence ministry issued a statement stressing its officers' "full support" for the president amid "attempts to interfere in internal affairs."

The defence ministry also said it was beginning drills involving fighter jets and air-defence forces and was also calling up military reservists for exercises next week.

Russian foreign ministry spokeswoman Maria Zakharova dismissed Minsk's actions as putting on a "show."

- 'Poor girls' -

The leading opposition candidate in the tense polls, 37-year-old Svetlana Tikhanovskaya, is running in place of her jailed husband and has drawn massive crowds at rallies across Belarus in an unprecedented display of frustration with Lukashenko's rule.

Tikhanovskaya, a stay-at-home-mother, has teamed up with the wife and campaign chief of two other opposition activists who have been barred from running.

In his address, Lukashenko denigrated the women as "these three poor girls".

"They don't understand what they are saying or what they are doing," Lukashenko said.

Critics slammed the strongman leader's scare tactics, saying he could not offer the country a new path.

"Under Lukashenko, Belarus is not developing, and there is no chance that anything will change," said opposition politician Nikolai Kozlov.

Early voting began on Tuesday and the election commission said that almost seven million eligible voters could cast ballots at more than 5,700 polling stations.

- Tired of 'stagnation' -

Independent observers claimed the authorities would pressure public-sector employees to vote for Lukashenko during the early voting period and carry out widespread falsifications before the main election day.

Dmitry, a 33-year-old builder who declined to give his last name, said that Belarusians want "to move forward, develop".

"People are tired of living in this time of stagnation," he told AFP in Minsk.

Tikhanovskaya has called on her supporters to vote on Sunday to avoid manipulation before the count and to wear a white bracelet so independent monitors can easily identify them.

The Organization for Security and Cooperation in Europe has not recognised any elections in Belarus as free and fair since 1995.

The OSCE said it will not send observers to the vote after Belarus failed to issue an invitation in time. The organisation also raised concerns over intimidation and arrests of the opposition.