A Russian court added two years to the 7.5-year prison term of Lilia Chanysheva, a former associate of late opposition leader Alexei Navalny, on extremism charges.
The hearing was held in closed doors, extending her sentence to a total of 9.5 years.
The Kremlin's crackdown on dissent, including opposition activists, independent journalists, and government critics, has intensified since Russia's annexation of Crimea in 2014.
Hundreds of people have been charged and fined or briefly jailed for protesting against the war in Ukraine and making critical remarks.
One of those charged is Chanysheva, who was convicted of extremism-related offenses last summer.
Her arrest in November 2021 came after a court ruling earlier that year designating Navalny's Foundation for Fighting Corruption and his regional offices as extremist organizations.
Navalny, a prominent opposition figure and Putin critic, died in prison in February while serving a 19-year sentence on similar charges.
Opposition figures and Western leaders accused the Kremlin of being responsible for the death of Russian opposition leader
Alexei Navalny.
In response, a judge extended the sentence of Navalny's spokeswoman, Vasilyina Chanysheva, who is currently in prison.
Chanysheva's extended sentence was described as "horror" and "monstrous" by Navalny's spokeswoman, Kira Yarmysh.
Moscow officials have denied any involvement in Navalny's death and rejected the accusations.