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 on Thursday.

In Russia, participation in unauthorised demonstrations can lead to a fine or several days in jail
In Russia, participation in unauthorised demonstrations can lead to a fine or several days in jail AFP / Kirill KUDRYAVTSEV

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

The opposition staged demonstrations in dozens of Russian cities, with the largest rallies taking place in Moscow.

In Russia, participation in unauthorised demonstrations can lead to a fine or several days in jail
In Russia, participation in unauthorised demonstrations can lead to a fine or several days in jail AFP / Kirill KUDRYAVTSEV

The OVD-Info monitoring group, which tracks detentions at opposition protests, said that by Thursday morning police had detained "more than 1,783 people in 97 cities".

Police officers detain a protester during a rally in support of jailed Kremlin critic Alexei Navalny, in central Saint Petersburg
Police officers detain a protester during a rally in support of jailed Kremlin critic Alexei Navalny, in central Saint Petersburg AFP / Olga MALTSEVA

In Russia, participation in unauthorised demonstrations can lead to a fine or several days in jail.

The majority of detentions -- 805 -- took place in Saint Petersburg, where police violently dispersed crowds with shock sticks.

Opposition supporters hold their cell phones during a rally in support of jailed Kremlin critic Alexei Navalny in central Moscow
Opposition supporters hold their cell phones during a rally in support of jailed Kremlin critic Alexei Navalny in central Moscow AFP / Kirill KUDRYAVTSEV

Navalny's press secretary Kira Yarmysh was among those detained. She was given a 10-day stint behind bars for calling on people to join unauthorised rallies.

Key Navalny aide Lyubov Sobol was also taken into police custody ahead of the rally in Moscow and is due to appear in court later Thursday.

Wednesday's rallies did not match in size those held in the winter when Navalny was arrested after returning to Russia from Germany.

Tens of thousands took to the streets despite freezing temperatures while more than 11,000 people were detained.

Navalny, 44, was arrested when he returned to Russia in January after months recovering in Germany from a near-fatal nerve agent poisoning he blames on the Kremlin -- an accusation it rejects.

His health has been failing since he launched his hunger strike to demand proper medical care for a range of ailments, including back pain and numbness in his limbs.