An anti-war politician who sought to oppose Vladimir Putin in Russia's most recent presidential election has been detained, according to updates from his social media profile.

Boris Nadezhdin was escorted to a police facility in a community west of Moscow on Monday morning, shortly after declaring his intent to stand in the September parliamentary elections for the Duma.

"They took him from his home," his press secretary informed BBC Russian. "The reason for his detention is unknown."

The previous week, Nadezhdin received a "foreign agent" designation from the justice ministry and faced accusations of disseminating inaccurate details about the Russian government while urging participation in unsanctioned protests.

Such a designation would have barred him from contesting the September elections.

"What is there to say? I will continue to live and fight," he remarked.

"This is unlikely to change anything in my political biography. I will continue to run for the State Duma and collect signatures."

At the start of 2024, Nadezhdin pursued a presidential bid centered on an anti-war platform that advocated ending the conflict in Ukraine.

During that period, he informed the BBC of backing from "dozens of millions of people" who opposed "Russia to be in this track of authoritarianism and militarism."

He further stated that, upon election as president, his initial priority would involve halting the Ukraine conflict before working to normalize ties between Russia and Western nations.

Yet his critiques of Putin stayed restrained, prompting speculation that the Kremlin might permit his candidacy to project an image of electoral fairness.

Nadezhdin was ultimately excluded from the ballot by the Russian electoral commission weeks ahead of the vote, citing flaws in over 15 percent of the signatures submitted with his application.

He challenged the decision but could not proceed, mirroring the fate of other viable opposition candidates.

On 18 March 2024, Putin secured a decisive win that secured his fifth term in office.

The subsequent presidential election is set for 2030, when Putin will reach age 78. A 2020 constitutional change adjusted term limits, permitting him to stay in power through 2036.

Earlier this year, amid Kremlin curbs on internet access for millions and a worsening economic situation, Nadezhdin noted to the BBC that citizens were "beginning to understand that there is a direct connection between their everyday problems, like healthcare, food prices, problems with internet and the politics of Vladimir Putin."

The Kremlin maintains extensive dominance over Russia's political environment, making any serious challenge to Putin's authority improbable.

Opposition voices who might have presented alternatives to Russian voters now find themselves imprisoned, abroad in exile, or deceased.