Russian leftist Sergei Udaltsov charged with conspiracy
Russian leftwing opposition leader Sergei Udaltsov has been charged with plotting mass disorder, and faces up to 10 years in prison if convicted.
Speaking before he was charged at the Investigative Committee (SK), a federal police agency modelled on the FBI, he said he had committed no crime.
"Putin regime on trial here," he wrote on Twitter. "Come to SK to back me & other political prisoners!"
Two other activists are already in custody over the same allegations.
Mr Udaltsov, who is subject to a travel ban, was not arrested and later left the SK.
The plot allegation was first aired in a documentary on Russia's NTV channel, which the SK cited as evidence.
Activists are accused of seeking funds from Georgia, with which Russia fought a brief war in 2008, to stoke unrest in Russia.
The arrest of one of them, Leonid Razvozzhayev, who was apparently snatched off the street in the Ukrainian capital Kiev last Friday before being brought to Moscow, has caused concern in the US and outrage among human rights groups.
'I will not run'
Mr Udaltsov, who leads the Left Front coalition, is a familiar figure from street protests in Moscow, for which he has served short periods in detention in the past.
He condemned the case before going into the SK office.
"My comment is very short - this case is based on tortures, it's shameful, it hurts Russia's image," he said.
Mr Udaltsov's wife and children are currently staying in neighbouring Ukraine.
"If somebody expected me to run across the border like a scared dog, they will not see this," he said on Friday. "I have not committed any crime."
If he was arrested, he added, he hoped there would be "mass protests".
"As for me - I'll be ok, I hope everything will be fine and Russia will be free and that's what I wish you all," Mr Udaltsov said.
Konstantin Lebedev, an aide to Mr Udaltsov, was charged earlier and placed in custody for two months.
Mr Razvozzhayev is currently being held in Moscow's Lefortovo prison.
He vanished in Kiev last Friday while consulting UN officials about seeking political asylum.
Human rights activists who saw him in prison say he told them he had been bundled into a van before being driven across the border into Russia, where he was allegedly tortured into making a false confession.
By his own account, he signed a confession while in handcuffs.
Human Rights Watch has asked the Ukrainian authorities to make a full investigation.
"For an asylum-seeker to simply vanish while lodging his asylum claims and then reappear in the country he fled is profoundly shocking," said Hugh Williamson, the organisation's Europe and Central Asia director.
"There needs to be a serious investigation to determine whether any Ukrainian officials were involved and to hold accountable any who played a role."
Ukraine's main opposition party has accused President Viktor Yanukovych of sanctioning Mr Razvozzhayev's detention by Russian agents.
"The special services of a foreign state are operating on Ukraine's territory," said Arseniy Yatsenyuk, an ally to imprisoned Ukrainian opposition leader Yulia Tymoshenko.
Ukraine's national security agency said earlier it had received no request to detain Mr Razvozzhayev, Ukrainian media report, while the interior ministry in Kiev said it had not been involved.
The country is holding a general election on Sunday.