MOSCOW (AP) — Police in the Russian capital have detained dozens of people at a protest against political repression outside the headquarters of the Federal Security Service.

The OVD-Info group that monitors arrests at demonstrations in Russia said 49 people were detained on Saturday.

It was not immediately clear what charges would be filed.

The detentions came as people stood in line to take part in a single picket protest. Russian law allows lone picketers without prior permission.

Rotating single pickets, in which each person stands for a short period before giving way to the next, is a frequent strategy.

The security service is the main successor to the Soviet KGB and its headquarters building on Lubyanka Square has strong symbolic resonance.