A member of the Left Front opposition group was snatched off the street in the Ukrainian capital of Kiev on Friday.
A UN official was quoted in the Russian press saying that the activist, Leonid Razvozzhaev, had come to the UN refugee agency’s office in Kiev to request political asylum after authorities said they were seeking his arrest.
Mr Razvozzhaev went out for lunch and did not return, the official said.
In a video shot as he was being stuffed into a police van in Moscow after a court sanctioned his arrest on Sunday, Mr Razvozzhaev told journalists he had been tortured in police custody. “Tell everyone they tortured me. For two days. They smuggled me in from Ukraine,” he is heard shouting.
The prosecutor’s office denied the use of torture, saying a medical examination of Mr Razvozzhaev had revealed no injuries.
Vladimir Markin, a spokesman for the prosecutor’s office, said Mr Razvozzhaev had turned himself in on Sunday and written a 10-page confession to inciting mass disturbances and receiving foreign funds.
Ukraine’s security service denied taking part in Mr Razvozzhaev’s capture, according to an anonymous comment on news service Interfax Ukraine.
Sergei Udaltsov, leader of the Left Front, wrote in a blog post on Monday that the actions of the authorities represented “the start of a terror campaign against dissidents. It is not just arrest and searches, it is torture, kidnapping and detention on the basis of fabricated proof”.
Mr Udaltsov is the target of a police investigation into inciting mass disturbances during a demonstration on May 6, where a number of demonstrators and police were injured. No charges have been filed against him, although his deputy was also arrested last week and is being held for two months on charges of incitement.
The increasingly tough tactics underline the regime’s determination to end the protest movement, but analysts questioned why the Kremlin was so desperate to crush the Left Front organisation.
“A bunch of leftwing radicals does not present any danger to the government,” said Masha Lipman, a political analyst at the Carnegie Moscow Center, a think-tank. “It seems, though, that they do not want to take the risk of finding out what would happen if these guys are left to their own devices. Perhaps they would become more popular.”
Mr Udaltsov was the subject of a documentary film shown on state TV earlier this month, which accused him of accepting money from foreign intelligence agencies. Grainy footage showed him allegedly meeting a Georgian government official identified as Givi Targamadze, who promised him funds and suggested far-fetched actions such as taking over the Russian city of Kaliningrad.
Mr Udaltsov and Mr Targamadze deny such a meeting took place, though Mr Udaltsov did say he met a Georgian man in Minsk, Belarus, and discussed “legal” methods of financing his movement.
Soon after the film was shown, the police investigated Mr Udaltsov and his followers on charges ranging from terrorism to inciting mass disturbances.
By Charles Clover
(Source: Financial Times)