Tuesday, a Moscow court sentenced Alexei Navalny, the most prominent opponent of President Vladimir Putin, to nearly three years in prison, in a ruling condemned by several Western countries. 

The court ruling is likely to exacerbate tensions with the West, which is demanding the release of the Russian dissident.

Judge Natalia Repnikova ordered the transfer of a suspended 2014 sentence condemning Navalny to fraud and a final prison sentence, according to an AFP correspondent who attended the court session.

The court considered that the opponent violated the conditions of judicial control attached to his sentence, which was also mentioned in the requests of the Prisons Authority and the Prosecution Office.

This prison sentence is the longest for Navalny, the most prominent opponent of President Vladimir Putin, as previous punishments against him did not exceed days or weeks.

During the hearing, Navalny accused the Russian president of trying to intimidate his opponents. He emotionally repeated accusations that authorities had tried to kill him with Novichok last summer.

- "To scare millions" -

"They are putting one person behind bars to scare millions," Navalny said. 

He believed that Putin wanted to be seen as a great world leader and historical figure, but instead "he will be remembered by history as the poisoner of underwear."

The anti-corruption activist was arrested on January 17th upon his return to Moscow from Germany.

Tuesday evening, a human rights organization announced that the Russian authorities had arrested more than 1,050 people during demonstrations that took place in several parts of the country, especially in the capital, Moscow, to protest Navalny's conviction.

OVD-Info, the non-governmental organization specializing in following up protests, said that the overwhelming majority of these detainees (865 people) were arrested in Moscow, where security forces forcibly dispersed demonstrators who went to protest against Navalny's prison sentence.

French President Emmanuel Macron rejected the ruling against the Russian opposition and demanded "his immediate release."

Macron wrote on Twitter that "the conviction of Alexei Navalny is rejected. The political dispute was never a crime. We call for his immediate release. Respect for human rights such as democratic freedom is not negotiable."

Later, Macron reposted the same tweet in Russian.

His position intersects with those of other European leaders who demanded the immediate release of Navalny after his conviction in a Moscow court.

It is expected that the European Union Foreign Minister Josep Borrell will take his stance to Russia, where he arrives Thursday evening on a two-day visit until February 6.

In turn, German Chancellor Angela Merkel called for the immediate release of Navalny and an end to the repression of demonstrations organized by the Russian opposition.

"The sentence against Alexei Navalny is very far from the rule of law rules. Navalny should be released immediately. Violence against peaceful protesters must stop," the chancellor wrote in a Twitter message posted by her spokesperson, Stephen Siebert.

Britain also demanded the "immediate and unconditional release" of Navalny, condemning the "cowardly" and "perverted" judicial decision.

"Alexei Navalny's decision to return to Russia after his poisoning was truly a courageous and fair act," British Prime Minister Boris Johnson said in a tweet.

He added that "the decision issued by the court today is pure cowardice and does not meet the most basic standards of justice," stressing that "the opponent of Russian President Vladimir Putin must be released immediately."

The UN Security Council has abandoned efforts to hold an informal meeting this week on the Navalny case, officials said Tuesday.

- Anti-corruption investigations -

While he did not hold any official office by election, Navalny was known for investigating corruption and exposing the lifestyle of Russia's wealthy elite.

Two days after his arrest last month, his team released an investigation into a luxury seafront property that Navalny said was awarded to Putin as part of a billion-dollar project financed by close associates at the head of state institutions.

The report was posted with a video posted on YouTube, with more than 100 million views.

Putin denied that he was the owner of the property, and last week, a billionaire businessman close to him, Arkady Rutenberg, said he was the owner of the property, confirming that he was converting it into a hotel.

Also read: Russian prosecutors seek to keep Navalny in prison despite protests