More than 1,700 people were detained by police at rallies in support of jailed Kremlin critic Alexei Navalny in dozens of cities across Russia, an independent monitor reported Thursday.

A protester wearing a face mask takes part in a demonstration in support of Navalny outside the Russian Embassy in London, Britain, April 21, 2021.

Thousands of people took to the streets Wednesday evening to demand freedom and proper medical attention for Navalny, who has been on hunger strike for three weeks in a penal colony outside Moscow.

A woman holds a poster saying "Against Putin. Against fascism. Freedom to Navalny" during an opposition rally in Moscow, Russia, April 21, 2021.

Opposition supporters attend a rally in support of jailed Kremlin critic Alexei Navalny, in Moscow, Russia, April 21, 2021.

Russian riot police officers block a street during a rally in support of jailed Kremlin critic Alexei Navalny, in central Saint Petersburg, Russia, April 21, 2021.

Yulia Navalnaya, the wife of Russian opposition leader Alexei Navalny, attends a rally in support of her husband, in central Moscow, Russia, April 21, 2021.

A woman holds a "Free Navalny" sign during a protest against Russia's jailing of opposition leader Alexei Navalny, in Tel Aviv, Israel, April. 21, 2021.

A demonstrator is taken away by law enforcement officers during a rally in support of jailed Russian opposition politician Alexei Navalny in Saint Petersburg, Russia, April 21, 2021.

A demonstrator holds a placard during a protest in support of Kremlin critic Alexei Navalny, Prague, Czech Republic, April 21, 2021.

Russian police officers block a street during an opposition rally in Moscow, Russia, April 21, 2021.

People gather in front of the Russian embassy in Warsaw to show their support for Russian opposition leader Alexei Navalny, demanding his release from jail, April 21, 2021.

Russian riot police officers detain men during opposition rally in St. Petersburg, Russia, April 21, 2021.

A Russian riot police officer patrols a street during a rally in support of jailed Kremlin critic Alexei Navalny, in Moscow, Russia, April 21, 2021.

Demonstrators hold placards during a protest in support of Kremlin critic Alexei Navalny in Prague, Czech Republic, April 21, 2021.

A supporter waves the Russian national flag and shouts slogans during the opposition rally in support of jailed opposition leader Alexei Navalny in the center of Moscow near Red Square, Russia, April 21, 2021.

People clash with police during a protest in support of jailed opposition leader Alexei Navalny in St. Petersburg, Russia, April 21, 2021.

A couple wears face masks reading "free Navalny" during a protest against Russia's jailing of opposition leader Alexei Navalny, in Tel Aviv, Israel, April 21, 2021.