The United States expressed its concern late Thursday at the detainment of around 150 opposition activists in Moscow and St. Petersburg.

The gatherings were part of the so-called "Strategy 31" marches organized for the last day of every month with 31 days, in reference to Article 31 of the Russian Constitution which allows peaceful demonstrations.

Among the arrested in St. Petersburg was prominent opposition leader Boris Nemtsov.

In St. Petersburg, a police helicopter hovered over the anti-Kremlin protesters, whipping up dust and knocking several people off their feet. In Moscow, hundreds of police packed the city's Triumph Square, the traditional site of protests in the capital, and dragged many demonstrators into police trucks.

US stresses need for 'freedom of expression'

The reaction from the US was swift, with National Security Council spokesman Tommy Vietor reiterating "the importance of embracing and protecting universal values, including freedoms of expression and assembly, enshrined in the Russian Constitution as well as in international agreements Russia has signed.

"Freedom of assembly and freedom of expression are not only vital ingredients of sound political systems, they are essential for economic modernization and broad-based prosperity," he added.

"Without freedom of assembly, it will be impossible to foster genuine competition during Russia's upcoming parliamentary elections in December."

Russian authorities place strict limits on the size of protests and any mass gatherings that have not been approved by authorities.

Author: Darren Mara (Reuters, AFP)
Editor: Martin Kuebler