MOSCOW — Protesters on Sunday again flooded into the capital of Belarus and towns across the country, signaling the depth of popular anger at President Aleksandr G. Lukashenko, an iron-fisted leader who, fortified by strong support from Russia, has shown no sign of bending.
The Belarus protests have mobilized large numbers of people for nearly a month, since a disputed presidential election, and have been dominated by calls for Mr. Lukashenko to resign. They have struggled, though, to bend the will of an authoritarian leader who has rejected all compromise and scorned his critics as “rats,” “tricksters” and “traitors.”
The crowd on Sunday in Minsk, the Belarusian capital, appeared to be as large as those on three previous Sundays, when more than 100,000 people gathered to protest what they believe was a blatantly rigged presidential election on Aug. 9 and to demand that the declared victor, Mr. Lukashenko, cede power.
Defying government warnings, protesters in Minsk paraded up to lines of riot police officers blocking major avenues, shouting, “Shame!” and “Go away.” They waved red and white flags, which served as the national flag until Mr. Lukashenko replaced it 25 years ago — a year after he took office — with a more Soviet-looking standard.
Smaller protests were reported in Brest, a city in the west on the border with Poland; Grodno, a hotbed of opposition sentiment in the northwest; Gomel, a town in the southeast near Russia where Mr. Lukashenko has staged a number of pro-government rallies, and several other towns.
In an effort to reduce the size of the protests in Minsk, the authorities sealed off streets in the city’s center, shut down metro stations and deployed large groups of riot police officers. They arrested scores of people but mostly refrained from the heavy-handed violence that was seen when the protests began last month.
Russia’s Interfax news agency reported that several people were injured when security officers broke up a protest outside a state-run tractor factory. RIA-Novosti, a state-controlled Russian news agency, quoted the Belarusian Interior Ministry as saying that “hundreds” of people had been arrested in Sunday’s protests.
The number of demonstrators in Minsk and elsewhere gave weight to an assertion on Friday by Svetlana Tikhanovskaya, Mr. Lukashenko’s main rival in the disputed election, who said that, “it is impossible to force the people to back down,” and that the protest movement had “reached the point of no return.”
But it is unclear how Ms. Tikhanovskaya, who fled to neighboring Lithuania after challenging the election result, and other opposition leaders can force Mr. Lukashenko to bow to undimmed public anger over his claims of a re-election landslide.
Looking for ways to increase pressure on Mr. Lukashenko, Ms. Tikhanovskaya told the United Nations during an informal meeting by video link last week that the president was “desperately clinging to power” and needed to be prodded by the international community. She urged the United Nations to send international monitors to Belarus, something that Russia, a permanent member of the Security Council, would almost certainly prevent.
The Belarusian government, calculating that it can sap the energy of the protest movement by removing its leaders, has arrested most of Mr. Lukashenko’s most outspoken opponents and forced others to leave the country.
On Saturday, Olga Kovalkova, an ally of Ms. Tikhanovskaya, became the latest opponent of Mr. Lukashenko to be forced to leave Belarus. Arrested two weeks ago in Minsk, she reappeared on Saturday in Poland. She told a news conference in Warsaw that Belarusian security officials put her head in a hood, bundled her into a car that drove across the country and then dumped her on the border with Poland. The Belarusian Interior Ministry told a Russian news agency that she had been released for medical reasons.
With Belarusian security forces showing no sign of wavering in their support, Mr. Lukashenko has in recent days moved to shore up support from President Vladimir V. Putin of Russia, with whom he has often had testy relations. Mr. Putin announced late last month that he had formed a reserve force of security personnel ready for action in Belarus if “the situation gets out of control.”
Mr. Lukashenko has reshuffled the leadership of Belarus’s main security agency, which goes by its Soviet-era name, the K.G.B., appointing a new chief, Ivan Tertel, who is known for his close ties to Russia’s Federal Security Service.
Mr. Tertel’s predecessor, Valery Vakulchik, presided over the arrest in July of 33 Russian citizens whom he described at the time as mercenaries sent to Belarus by Moscow to stir up unrest before the presidential election.
The Russian fighters have since been freed, and both Moscow and Minsk have sought to put the episode behind them, saying it was orchestrated by Ukraine and the United States to try to drive a wedge between Mr. Putin and Mr. Lukashenko.
In a bizarre effort to display his loyalty to Moscow, Mr. Lukashenko on Wednesday presented an alternate theory on the recent poisoning of the Russian opposition leader Aleksei A. Navalny, who is being treated in Berlin. He told Russia’s prime minister, Mikhail Mishustin, that Germany had plotted with Poland to fabricate the poisoning so as to deter Mr. Putin from meddling in Belarus.
As evidence, he offered a recording of what was described as an intercepted telephone call between German and Polish officials. The recording, featuring two men, identified as Mike and Nick, speaking English, was released on a social media channel tied to Mr. Lukashenko’s administration and widely dismissed as a risible fake.
And in another gesture toward Moscow, Belarusian security officials have arrested Irina Sukhi, an environmental activist who has campaigned against a nuclear power station built in Belarus near the border with Lithuania by Rosatom, a state-owned Russian company. The arrest was reported on Sunday by Ms. Sukhi’s daughter, Sophie Sadovskaya.