A well-known Russian opposition blogger and radio host was beaten outside his home in Moscow, his spokesman said, as Kremlin critics say they are subject to a growing number of attacks.
Yegor Zhukov, 22, was handed a suspended sentence last summer on extremism charges for making videos criticising President Vladimir Putin amid huge protests calling for fair elections.
Zhukov's team posted a picture on Telegram of his bloodied and swollen face saying he was attacked and beaten near his home Sunday evening.
"According to eyewitnesses, he was attacked by two thugs who disappeared on scooters," Zhukov's spokesman Stas Toporkov said.
The opposition figure filed a complaint with police and underwent medical checks afterwards, according to the Interfax news agency.
Zhukov was arrested in August last year for his role in mass protests that erupted after independent and opposition candidates were barred from contesting local elections.
A politics student at the time, he was released under house arrest and charged with making online calls for extremism.
Earlier on Sunday, Zhukov said he had been excluded from a Masters degree course at the prestigious Higher School of Economics in Moscow, shortly after enrolling.
He said that a university administrator told him the decision had been taken "on orders from above".
Russia's opposition have complained of a growing number of attacks and punitive legal cases against Kremlin critics following a vote on changes to the constitution that allow Putin to extend his rule.
Leading opposition leader Alexei Navalny is being treated in a hospital in Berlin for a suspected poisoning and his allies hold Putin ultimately responsible.