Demonstrators have been prepared to risk being taken away by police on a daily basis since Russia’s invasion of Ukraine last Thursday.
The protests show little sign of abating despite a police crackdown.
The OVD-Info human rights group that tracks political arrests says there have been 6,440 detentions in anti-war demonstrations in different cities across the country.
Kremlin spokesperson Dmitry Peskov sought to downplay the scale of the protests, saying that while Putin "hears everyone's opinion", he also knows "the share of those who have a different point of view and those who are sympathetic to such a necessary operation".
Groups of protesters in St Petersburg were seen being detained by riot police on Monday.