Radio Liberty says two jailed Tajik opposition politicians have been placed in solitary confinement after sending a letter to President Emomali Rahmon from a penal colony.

Two imprisoned members of the banned Islamic Renaissance Party of Tajikistan (IRPT) -- Zubaidullo Roziq and Rahmatullo Rajab -- told their relatives that the administration of the penal colony in Vahdat near Dushanbe had ruled to place them in solitary confinement for two months as punishment for sending a letter to President Rahmon without obtaining preliminary permission from the warden.

In their letter, Rajab and Roziq "revealed certain details of their case, trying to prove their innocence," their relatives told RFE/RL on November 11.

An official with the state penitentiary service confirmed to RFE/RL on condition of anonymity that the two men are currently in solitary confinement for "violating regulations."

Dozens of IRPT officials and supporters have been prosecuted and many imprisoned in recent years, prompting criticism of Rahmon's government from rights groups.

Rajab and Roziq were arrested in 2015 and sentenced to 28 and 25 years in prison, respectively, after a court found them guilty of involvement in a purported insurrection against Rahmon's government led by Army General Abduhalim Nazarzoda.

The IRPT has denied any links to the deadly events and called the imprisonment of its members and leaders politically motivated.  The IRPT was declared extremist and banned in 2015.