Russian police have detained more than 200 people near a Moscow court which is considering whether to jail Kremlin critic Alexei Navalny, monitors say.
Mr Navalny said in court the charges against him were fabricated and again blamed President Vladimir Putin for a nerve agent attack on him last August.
Mr Putin “will go down in history as a poisoner”, he said vehemently.
The hearing is to decide whether to turn Mr Navalny’s suspended sentence into an actual prison term.
He could face up to three-and-a-half years, in a case that has sparked nationwide protests.
The verdict is expected at 20:00 local time (17:00 GMT), a court spokeswoman has said.
Many riot police, including some on horses, are deployed outside the court.
The arrests were reported by the Russian OVD-Info monitoring group, which documents police activities, and by the Moscow Public Monitoring Commission (ONK), a human rights body.
Mr Navalny’s return to Russia on 17 January triggered mass protests in support of him, many of them young Russians who have only ever experienced President Putin’s rule.
Mr Navalny has been accused of breaking the terms of a 2014 suspended sentence for embezzlement that required him to report regularly to Russian police. His lawyers say the accusation is absurd as the authorities knew he was recovering in Berlin from the nerve agent attack that nearly killed him in Russia.
Addressing the court on Tuesday, Mr Navalny said the case was being used to frighten the opposition: “This is how it works: they send one to jail to intimidate millions.”
On the Novichok chemical attack, he said: “Using the FSB [Federal Security Service of Russia], Putin attempted to commit murder. I’m not the only one – many know this already and many others will. And this is driving the thieving little man in the bunker crazy.
“No matter how much he tries to look like a geopolitician, he took offence at me because he will go down in history as a poisoner.”
The Kremlin has denied any involvement, and rejects the conclusion by Western experts that Novichok – a Russian chemical weapon – was used.
In an angry exchange with a prosecutor in court, Mr Navalny said that in January-August 2020 he had shown up at the probation service regularly as required. “And you were happy with that!” he exclaimed.
In November 2016 Mr Navalny received a payout from the justice ministry worth about €53,000 (£47,000), in line with a European Court of Human Rights (ECHR) ruling that his rights had been violated in the prosecution for alleged embezzlement.
At the scene: Navalny defiant from a glass cage
In Room 635 of the Moscow City Courthouse, four police officers have been guarding a glass cage. Locked inside is President Putin’s most ferocious critic.
For much of the time Alexei Navalny has been following proceedings in silence: standing with his arms folded. Sometimes he has interjected.
“Why are you deceiving the court by saying you didn’t know where I was?” Mr Navalny responded when the Moscow Prison Service claimed he had gone into hiding in Germany. “You had my address, my contact details.”
Several times the prosecutor has interrupted the defence lawyers, complaining about their line of questioning.
On the courtroom wall above me is a portrait of a famous Russian judge from tsarist times, along with the quotation: “Words are one of the greatest weapons of man.”
After his “Putin’s Palace” video notched up more than 100 million views online, Alexei Navalny may well agree.
Western diplomats are attending the hearing. The EU has condemned the mass arrests of Navalny supporters, and EU foreign policy chief Josep Borrell is to visit Moscow on Thursday for official talks.
Commenting on the court hearing, Kremlin spokesman Dmitry Peskov said “we hope that such nonsense as linking the prospects of Russia-EU relations with the resident of a detention centre will not happen”.
Just before the hearing began, Mr Navalny praised his wife Yulia, who is attending in court. She was fined 20,000 roubles (£190; $260) on Monday for having joined the pro-Navalny protesters at an “unauthorised” rally.
“They said that you had seriously violated public order and were a bad girl. I’m proud of you,” Mr Navalny said, quoted by Reuters news agency.
Mr Navalny accuses Mr Putin of running an administration riddled with corruption, and recently released a YouTube video featuring an opulent Black Sea palace which, he alleged, was a Russian billionaires’ gift to the president.
Some protesters on Sunday brandished gold-coloured toilet brushes, a symbol of their anger about the palace.
On Saturday Arkady Rotenberg, a billionaire businessman close to Mr Putin, said he owned the palace and had bought it two years ago.
The OVD-Info group said police detained more than 5,000 people at pro-Navalny protests in 86 cities across the country on Sunday. For a second weekend, crowds defied bitter cold and a massive deployment of riot police.
OVD-Info says it is an independent Russian media project, which gets crowdfunding in Russia and its donors include the Memorial human rights group and the European Commission.
Mr Navalny is already serving a 30-day sentence in connection with the embezzlement case, which he denounces as politically motivated.
In recent days police have arrested many of Mr Navalny’s top aides, who assist him in his Anti-Corruption Network (FBK).