Dozens of people holding single-person pickets near the Moscow headquarters of Russia’s Federal Security Service (FSB) have been detained by Moscow police, including a prominent human rights activist.

Mostly young protesters turned up on March 14 in the Russian capital to protest what they say is political repression in the country.

Some unfurled signs calling the security service the "Federal Service of Lawlessness" while others shouted "Shame!"

The OVD Info website, which tracks detentions at political protests, listed more than 40 people as having been detained by police, adding that some were hurt in the altercations.

Veteran human rights campaigner Lev Ponomaryov was among those detained in the sweep by police, who said the action was not authorized.

According to the AFP news agency, the 78-year-old Ponomaryov had argued with police that pickets don't require authorization, before being led to a police bus.

The action was organized by supporters of men convicted this year on terrorism charges, many of whom said in court they had been tortured by the FSB.

A court in the Penza region last month handed down terms of between six and 18 years to seven young men who were accused of creating a terrorist organization known as Set (Network).

Russian investigators said the group planned to organize a series of explosions in Russia during the presidential election and the World Cup soccer tournament in 2018 "to destabilize the situation" in the country and to organize an armed mutiny.

They all denied the charges in court, and most said they had been tortured in custody with electrodes and beatings to extract confessions since their arrests in 2017 and 2018.

Two other defendants in the case are still on trial in St. Petersburg

With reporting by AFP