MOSCOW -- At least 350 people, including opposition leader Aleksei Navalny, were detained across Russia as they rallied in support of an election boycott on January 28.

The anticorruption crusader was dragged by police into a bus shortly after joining a rally of more than 1,000 people on Moscow's central thoroughfare on January 28, according to a live video feed from the scene.

"I've been detained. That doesn't matter. Come to Tverskaya [Street]. You're not coming out for me, but for yourself and your future," he wrote on Twitter afterward.

Hours later, Navalny tweeted that he had been released by police and driven to a metro station but would face a hearing on unspecified charges.

"A huge thanks to everyone who supported [me] and stood outside the police station. I heard your chants," Navalny tweeted. "You're awesome."

Thousands of Russians unhappy with the prospect of six more years under President Vladimir Putin took to the streets in dozens of cities, backing Navalny's call for a boycott of a March 18 vote that appears certain to hand Putin a new six-year term.

At the Moscow rally, 25-year-old Nastya told RFE/RL that it was her duty to take part in the rally, saying "You can't call choosing between one candidate [Vladimir Putin] an election."

Police warned earlier in the week that in the run-up to the election, they will be tough on demonstrators deemed to have broken the law.

OVD-Info, a website that that monitors law enforcement activity in Russia, said that 350 people were detained nationwide, including 66 in Ufa, 65 in Volgograd, 51 in Cheboksary, 31 in Kemerovo, 23 in Murmansk, 19 in St. Petersburg, and 16 in Moscow.

Most of them were released within hours.

"If we stay at home, then nothing will change for sure. If we take to the streets, then at least we have some kind of chance," said Nastya, who would not give her last name for fear of repercussions.

WATCH: Thousands of protesters gathered at Moscow's central Pushkin Square on January 28 to call for the boycott of Russia's upcoming presidential election.

A correspondent for RFE/RL's Idel.Reality website, Darya Komarova, was covering the protest in the Volga city of Cheboksary when she was detained.

In the Far Eastern city of Vladivostok, hundreds of people gathered in the main square, holding placards reading slogans such as "I will go to the elections when there's a choice" and "Putin is gobbling up Russia's future."

WATCH: Russian police detained a number of participants at a rally held on January 28 by Navalny supporters in the city of Tomsk. (RFE/RL's Russian Service)

Some demonstrators at the Moscow protest were chanting slogans including "Boycott the election" and "Russia without Putin."

Similar slogans were chanted in Russia's second city of St. Petersburg, where at least 1,000 people demonstrated.

WATCH: RFE/RL filmed the protests in the cities of Vladivostok, Irkutsk, Krasnoyarsk, Yekaterinburg, Kazan, and Saratov. (RFE/RL's Russian Service)

Tatyana Chertverikova, a 62-year-old teacher waving a placard reading "Wake up, Russia" told RFE/RL in Moscow, "I want an election at least, but they won't even give us that."

Vadim Yartsev, 17, said there was little hope the rally will lead to any improvement. "There won't be any response at all," he said. "They will ignore us"

Earlier, police shut down a TV studio at a Moscow office that had been broadcasting news bulletins about the protests, but Navalny's YouTube channel continued to provide live coverage.

Police forced their way into Navalny's Anticorruption Foundation in the capital, claiming a bomb threat and demanding the premises be evacuated, his supporters said.

Roman Rubanov, the foundation’s director, posted photographs on Twitter of police officers gathered outside the office door in a southeast Moscow business center and then bursting in by force.

Rubanov wrote that police officers accused one of the activists of planting a bomb.

One anchor, Dmitry Nizovtsev, was detained by police, according to video broadcast from the headquarters. Navalny's Moscow coordinator, Nikolai Lyaskin, also was detained, the Interfax news agency quoted him as saying.

Attempts by Navalny’s supporters to cover mass protests last year were thwarted by police raids.

In Navalny's headquarters in the southern city of Astrakhan, police seized leaflets calling for the election boycott and detained members of the staff, OVD-Info reported.

And several people were reportedly detained at Navalny’s headquarters in St. Petersburg.

Navalny called for the boycott after being barred from the March 18 presidential election due to a financial-crimes conviction that he and his supporters contend was Kremlin-engineered retribution.

He has dismissed the vote as the "reappointment" of Putin, who has been president or prime minister since 1999.

With the Kremlin controlling the levers of political power nationwide after years of steps to suppress dissent and marginalize political opponents, it is virtually certain that the election will hand Putin a new six-year term.

Political commentators say Putin, 65, is eager for a high turnout to strengthen his mandate in what could be his last stint in the Kremlin, as he would be constitutionally barred from seeking a third straight term in 2024.

Navalny has accused the rest of the field of presidential hopefuls of playing into Putin's hands and aiding what he says is a Kremlin bid to portray the vote as a legitimate, competitive contest.

In Moscow, Navalny had called on demonstrators to gather despite city authorities' refusal to grant permission for a rally there, setting the stage for a potential confrontation.

Moscow Office Searched

Ahead of the rally, police forced their way into Navalny’s Anticorruption Foundation in Moscow, claiming a bomb threat and demanding the premises be evacuated, his supporters said.

Roman Rubanov, the foundation’s director, posted photographs on Twitter of police officers gathered outside the office door in a southeast Moscow business center and then bursting in by force.

Rubanov wrote that police officers accused one of the activists of planting a bomb.

Navalny’s spokeswoman said she thought the raid was aimed at shutting down the work of a TV studio inside.

Attempts by Navalny’s supporters to cover mass protests in March and June last year were thwarted by police raids.

At Navalny's headquarters in the southern city of Astrakhan, police seized leaflets calling for the election boycott and detained members of the staff, OVD-Info reported.

And several people were reportedly detained at Navalny's headquarters in St. Petersburg.

The raids and detentions come days after a Moscow court ordered the closure of another foundation crucial to the presidential campaign Navalny has sought to conduct, and as reports of police searches of his campaign offices and harassment of his supporters mount.

On January 26, Russia's Supreme Court revealed that it had declined Navalny's appeal to be allowed to run for president.

On January 25, police issued a stern warning to antigovernment protesters. At a meeting with top Moscow police officials, First Deputy Interior Minister Aleksandr Gorovoi said that police will respect the right of citizens to hold public gatherings, as provided by the constitution and other legislation -- but emphasized they would "absolutely toughly...prevent violations of these laws."

Protests Go Ahead

In a blog post on January 27, Navalny urged people to come to the rallies on January 28, writing that "to stay at home is to send them [those in power] the signal: 'I'm ready to endure this for another six years.'"

He also wrote that in 80 percent of cases, authorities have granted permission for rallies at the requested sites for January 28, but not in Moscow or St. Petersburg.

Police have repeatedly cracked down on demonstrations organized by Navalny in the past. More than 1,000 people were detained in Moscow alone on March 26, 2017, when Navalny organized protests in some 100 cities nationwide.

Law enforcement authorities also cracked down hard at a protest in May 2012, the day before Putin returned to the Kremlin for his current term after a stint as prime minister.

Navalny appeared this week at a European Court of Human Rights hearing in his case against Russia over repeated incidents in which he has been detained and jailed.

Days before the police warning, a Moscow district court ruled on January 22 that the foundation Navalny and his allies have used to rent premises and pay salaries at campaign headquarters should be shut down. Navalny's campaign chief, Leonid Volkov, described the ruling as absurd and vowed to appeal.

That ruling came days after the Constitutional Court refused to review a complaint from Navalny over the Central Election Commission’s decision in December to bar him from the presidential election.

Navalny supporters have complained of an upsurge in harassment by the state in recent weeks, saying police have searched offices and seized pamphlets calling for an election boycott.

With reporting by Reuters