MINSK -- Police in Belarus have detained more than 100 people at opposition rallies in the capital, Minsk, and elsewhere after President Alyaksandr Lukashenka announced his government had thwarted a "revolution" amid a widening crackdown on opposition leaders and activists, including the arrest of a potential presidential challenger.

People were urged to turn out on June 19, the last day to sign ballot petitions for those seeking to run in the Belarusian presidential election on August 9, when Lukashenka, 65, will be seeking a sixth term in office.

Lukashenka, in power since 1994, is facing what experts say is his biggest challenge yet as the country struggles to contain the coronavirus after the president ignored calls to institute any social-distancing measures or restrictions.

In Minsk, several hundred people lined the streets on June 19 before police moved in to make arrests in the early evening, detaining not only opposition supporters but members of the media.

RFE/RL reporter Alyaksandra Dynko and her cameraman, Andrey Rabchyk, were detained while reporting live from the event.

Acting RFE/RL President Daisy Sindelar said the journalists' detentions represent "direct attacks on the independent press and the rights of Belarus citizens to be informed about important developments in their country."

There were also reports that Internet access had been disrupted for several hours in Minsk on June 19.

Elsewhere, police threatened protesters in the city of Mahilau with force, while in Homel demonstrators were told their gathering was illegal, according to local media.

According to the Belarusian rights NGO Vyasna (Spring), some 140 people were detained by police across Belarus on June 19.

Meanwhile, Lukashenka announced on June 20 that this government would raise pensions, although he did not disclose by how much.

"This isn’t populism for the sake of some election. I would never do that," the Belarusian leader was quoted as saying.

On June 19, Lukashenka claimed to have thwarted an attempt to foment revolution in the Eastern European country, which he has ruled with an iron fist for more than a quarter of a century.

Lukashenka told a government meeting that forces "in the East and West" were trying to destabilize Belarus but that their "masks have been torn off" and the "puppets and puppet masters abroad" identified.

His comments came a day after thousands of people took to Independence Boulevard in Minsk in what was dubbed a picket of solidarity after Viktar Babaryka, who headed the Russian-owned Belgazprombank for 20 years, was detained on suspicion of financial crimes, as well as his son who heads his presidential election campaign.

Belarusian authorities on June 15 took control of the bank and arrested more than a dozen top executives on charges of tax evasion and money laundering.

Babaryka, 56, has said the actions taken against Belgazprombank were part of an intimidation campaign conducted on “political orders.”

On June 19, the European Union called on Belarus to immediately release Babaryka and his son from detention and to guarantee full respect of the rule of law.

"Any investigation must be impartial and without political pressure," EU foreign policy spokesperson Peter Stano said in a statement.

In a post on Twitter, the U.S. Embassy in Minsk urged Lukashenka's government to "uphold its international commitments to respect fundamental freedoms."

The crackdown on Babaryka and Belgazprombank -- which is nearly 100 percent owned by Russian natural gas giant Gazprom and its affiliate Gazprombank-- comes as Lukashenka faces what experts say is one of the biggest challenges ever to his rule, which stretches back to 1994.

Belarus, with a population of some 9.5 million, has one of Europe’s highest infection rates for the coronavirus, which Lukashenka dismissed as a "mass psychosis" and ignored calls by the World Health Organization and others to institute any social-distancing measures.

The World Bank predicts that the Belarusian economy will contract by 4 percent this year as a result of the pandemic, while some informal, online polls put Lukashenka's public support at just 3 percent.

Lukashenka on June 4 named 46-year-old Raman Halouchanka, who previously oversaw military industries, as prime minister. The appointment came a day after Lukashenka, who had been promising a government shake-up ahead of the election, dismissed Syarhey Rumas along with his government.

Lukashenka said that "we need to clench our teeth" and to show more discipline in order to repair the economic damage inflicted by the coronavirus pandemic and "save what we have built."

In the election on August 9, Lukashenka, will be seeking a sixth term in office. No election either for president or parliament during his rule has been deemed free and fair by Western governments and institutions.

Babaryka has risen in popularity as the vote nears, and his election campaign says it has collected nearly 435,000 signatures -- more than four times the required 100,000 minimum to get on the ballot -- to support his bid to get on the ballot by a June 19 deadline.

The Belarusian Central Election Commission cleared 15 would-be candidates to collect signatures to get on the ballot, while rejecting others, including potential candidates like popular vlogger Syarhey Tsikhanouski and opposition politician Mikalay Statkevich, who challenged the authoritarian leader in 2010 and was imprisoned for protests that followed that disputed vote.

Both Tsikhanouski and Statkevich are now in jail, with Tsikhanouski facing a possible three-year prison term for organizing pro-democracy rallies.

The Committee for State Control (KDK) said on June 18 that Babaryka was arrested for allegedly attempting to influence witness testimony and illegally withdrawing large amounts of cash from bank accounts, among other things.

KDK head Ivan Tertel said that almost 20 employees of Belgazprombank had been arrested, adding that many of the suspects "confessed" that they had illegally transferred hundreds of millions of dollars to Latvia via a scheme organized by Babaryka.

Babaryka's election campaign staff said lawyers for the two men were not allowed to be present during the questioning, and that Babaryka's home in Minsk was searched by law enforcement officers.

In recent weeks, opposition rallies and gatherings in support of would-be candidates have attracted thousands of people across Belarus.

Several opposition activists, politicians, and bloggers were sentenced to up to 15 days in jail this week for taking part in what authorities called "unsanctioned rallies."

In his statement, Stano demanded that Belarus "refrain from any restrictions of the rights of potential candidates, avoid any detentions of peaceful protesters, and immediately release all arbitrarily detained activists."

"No potential candidate should be prevented from fulfilling the registration procedure due to politically motivated restrictive measures," he added.