MOSCOW, November 21 (RIA Novosti) – The number of prisoners spreading extremist ideas in Russian jails has increased by 40 percent since last year, a penitentiary service official said Thursday.

Some 426 prisoners are suspected of promoting extremist ideologies behind bars, said Valery Trofimov, head of the Federal Penitentiary Service’s education department.

The upsurge is due to an increase in the total number of people convicted on extremism-related charges – from 1056 last year to 1199 this year. “Such prisoners are put on the preventive register, they are supervised by most experienced personnel,” Trofimov said.