The leader of the opposition in Russia, Alexei Navalny, was detained on Saturday outside his home in Moscow ahead of planned nationwide anti-government protest rallies. His spokeswoman said he was later taken to a hospital with a suspected broken finger.

Navalny was detained on Saturday afternoon and taken to a nearby police station due to an unsanctioned rally in January, Kira Yarmysh said. Moscow police were not immediately available for comment on the detention or on Navalny’s reported injury.

Navalny, the most formidable political foe of Russian president Vladimir Putin, has called for nationwide rallies in early September to protest against the Russian government’s plans to raise the retirement ages for both men and women. The issue has outraged and united a wide range of Russians from different political backgrounds.

Navalny, who rose to prominence thanks to his investigations into official corruption, published a report on Friday alleging that at least $29m (£23m) had been stolen in procurement contracts for Russia’s National Guard, which is headed by Putin’s former bodyguard, Viktor Zolotov.