A Russian activist was forced to confess to plotting unrest against the rule of President Vladimir Putin under threats made to his life, rights workers said on Tuesday after visiting the man in a prison once run by the feared Soviet-era KGB.
Russian investigators said Leonid Razvozzhayev had been charged with preparing mass disorder, a day after they said he had voluntarily signed a confession offering details of how he and other protest leaders planned to carry out the unrest.
Civil groups and opposition leaders say the case is meant to sideline activists through legal pressure which has mounted since Putin returned to the presidency in May.
Statements from two rights workers who met Razvozzhayev paint a picture of him being abducted in Ukraine, bound in a minivan with tape and taken to a basement on his way to Moscow where he was forced by masked men to confess.
"Razvozzhayev said that he was ... in the basement of a house and they forced him to write a confession threatening him with a 'truth serum' and likewise threatening the lives and health of those close to him," Anna Karetnikova, deputy head of the Public Oversight Commission of Moscow, which monitors the treatment of detainees, was quoted as saying by RIA.
His high-profile case has been linked with those of other protest activists, including Sergei Udaltsov, a prominent protest leader who has played a major role in organising anti-Kremlin demonstrations.
Like Udaltsov, Razvozzhayev joined a protest movement that was sparked in December of last year by massive allegations that fraud had paved the way for the victory of Putin's United Russia party despite declining support.
They and another associate were named in a criminal investigation opened last week after a pro-Kremlin television station, using a hidden camera, aired footage alleging that they received money and orders from abroad to cause chaos in Russia.
All three could be sentenced to 10 years in jail if convicted.
Karetnikova said Razvozzhayev had asked for psychological treatment while in prison but that none was available in Lefortovo Prison, an infamous Soviet-era investigation ward.
"Thus far no one has been able to offer the detained psychological help," she said.
The case has additional political implications because the Investigative Committee which has taken up the case answers only to Putin.
Valery Borshchyov, head of the Public Oversight Commission of Moscow, said on television channel Dozhd that Razvozzhayev had said his arms and legs had been bound with tape and that he was not fed for three days or allowed to go to the toilet.
The man's supporters have disputed the accusations against him. A video posted on the Internet by opposition lawmaker Ilya Ponomaryov who employs Razvozzhayev as an aide shows him accusing the authorities of torturing him.
Since May, Putin has signed laws increasing restrictions on non-government organisations and raising fines for disorder at protests.
Ponomaryov said on his blog that Razvozzhayev had disappeared after visiting the office of the U.N. High Commissioner for Refugees in Kiev.
The United Nations Refugee agency issued a statement on Monday saying that it was "deeply concerned about the disappearance" of Razvozzhayev in Kiev on Friday.