Several suspects on trial over a deadly blast in the St. Petersburg subway in 2017 have alleged that they were tortured in custody as authorities sought people with connections to the man they say blew himself up.
The latest torture allegations emerged as 11 suspects went on trial on April 2, with a rights activist saying one of them recounted being taken to a "secret prison" and subjected to electric shocks and other abuse.
Yana Teplitskaya, a member of a group that defends the rights of prisoners, told news outlet Mediazona that Mukhamadyusup Ermatov said he was tortured after he was detained in St. Petersburg on April 5, 2017.
Ermatov and the other 10 defendants are charged with being accomplices in what Russian authorities say was a suicide bombing carried out by Akbarjon Jalilov, an ethnic-Uzbek Russian citizen born in Kyrgyzstan.
The blast on a subway car in Russia's second-largest city on April 3, 2017, killed 15 people and injured 67 others.
The defendants -- all natives of Central Asian former Soviet republics -- pleaded innocent on the first day of the trial at a military court.
According to Teplitskaya, Ermatov said that after he was detained he was kept in a "secret prison" -- apparently in or near Moscow -- for more than a month before his arrest was announced.
Among other alleged abuses, he said he was subjected to electric shock, kept with a sack over his head constantly, beaten, and deprived of food and water.
He said his brother Ibragimjon Ermatov was also tortured.
There was no immediate comment from the Federal Security Service (FSB) or other law enforcement agencies about the new allegations.
Two other defendants, brothers Abror and Akram Azimov, alleged earlier that they were tortured in custody after they were detained.
Rights activists and Western governments say that the torture of suspects and convicts by police and other law enforcement authorities is widespread in Russia.
In its annual report on human rights around the world, released on March 13, the U.S. State Department said that abuses in Russia in 2018 included "pervasive torture by government law enforcement personnel that sometimes resulted in death."