Russian opposition leader detained during anti-corruption protests

Russia's main opposition leader Alexey Navalny has been detained amid a tense anti-corruption protest in the heart of Moscow, according to his tweets.

Navalny downplayed his detention in a series of tweets and encouraged protesters to keep marching.

"Today we are discussing (and condemning) corruption, not the detentions. Well, I was detained. So what. It ok. There are things in life that are worth being detained for," Navalny tweeted.

In a series of tweets he added:

The protest in Moscow grew increasingly tense as the day progressed. More than 100 people had been arrested as of late Sunday afternoon, Russian state-run news agency Tass reported.

Similar demonstrations were planned in 100 cities across Russia on Sunday, according to the organizers.

Navalny praised turnouts to the protests in early-morning tweets.

"Far East started fine," he tweeted, referring to a photo of protesters gathering in the city of Vladivostok, located on Russia's far eastern coast. Navalny also shared photos and tweets from various parts of the country.

The protests are part of a campaign called "He is not your Dimon," using the diminutive form of the Russian name Dmitry to refer to Prime Minister Dmitry Medvedev.

Navalny has accused Medvedev of amassing a global property empire through various forms of corruption.

According to CNN, Navalny, who rose to prominence during the large-scale anti-government protests in Russia in 2011, has announced he plans to run for the Russian presidency in 2018.

In February, he was found guilty of embezzlement in a retrial of a case that dates back to 2013. Russian law prevents convicted criminals running for public office, but Navalny has appealed the verdict.

Sunday's demonstrations come at a time when the safety of critics of Vladimir Putin is under scrutiny. On Thursday, former Russian lawmaker and vocal critic of the Russian Government Denis Voronenkov was shot dead outside a luxury hotel in the Ukrainian capital Kiev.