Russian authorities are cracking down on supporters of opposition leader Alexei Navalny, who was arrested at a Moscow airport upon his arrival from Germany.
Kira Yarmysh, a Navalny spokeswoman, was detained overnight after calling for a demonstration, she announced on Twitter, adding that a court had determined that she would remain in custody for nine days.
Coordinators of Navalny's supporters' chapters in Vladivostok, Krasnodar and Kaliningrad were also detained.
Protests against Navalny's detention and state repression at the hands of President Vladimir Putin are scheduled to take place in about 70 Russian cities on Saturday.
Kremlin spokesman Dmitry Peskov warned members of the public not to participate in unsanctioned protests.
The coronavirus pandemic has meant that demonstrations have been banned in Russia for months.
Navalny, who on Sunday returned from Germany where he had been recovering from a near-fatal assassination attempt with the nerve agent Novichok, was sentenced to 30 days of pretrial detention at a snap trial on Monday.
The Russian judiciary says Navalny was sentenced for violating parole from an earlier sentence by travelling to Germany for his recovery.
The European Union's heads of state and government have discussed further sanctions against Russia over Navalny's detention, according to Lithuanian President Gitanas Nauseda.
"The Navalny case was indeed much discussed - there was also talk of sanctions," Nauseda said in Vilnius about the previous day's video conference.
European Council President Charles Michel, meanwhile, called Putin on Friday to reiterate the bloc's demands for Navalny's release.
"Russia must urgently proceed with full and transparent investigation into the assassination attempt on him," he said on Twitter.
Australian Associated Press
