Police officer assists a man who was injured during clashes between demonstrators and police in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police clashed with demonstrators and have arrested some hundreds in central Moscow during a protest demanding that opposition candidates be allowed to run for the Moscow city council. (AP Photo/ Pavel Golovkin)

MOSCOW (AP) — Russia's Investigative Committee has opened a criminal case into the weekend protest in Moscow where police detained nearly 1,400 people, indicating charges could be filed that carry prison sentences of up to 15 years.

No individuals were immediately named in the case that was announced Tuesday. The potential charges include calling for or participating in mass disorder.

An arrest-monitoring group says Russian police detained nearly 1,400 people in the Saturday protest against election authorities for excluding opposition candidates from the Sept. 8 ballot for the Moscow city election. Police beat some demonstrators harshly with truncheons.

In his first public comments on the disorder, Moscow Mayor Sergei Sobyanin said Tuesday the protesters "forced police to use force that in this situation was completely appropriate."

Protesters march during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police are clashed with demonstrators and have arrested some hundreds in central Moscow during a protest demanding that opposition candidates be allowed to run for the Moscow city council. (AP Photo/ Pavel Golovkin)
Police officers detain a woman during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police clashed with demonstrators and have arrested some hundreds in central Moscow during a protest demanding that opposition candidates be allowed to run for the Moscow city council. (AP Photo/ Pavel Golovkin)
Police block a street during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police clashed with demonstrators and have arrested some hundreds in central Moscow during a protest demanding that opposition candidates be allowed to run for the Moscow city council. (AP Photo/ Pavel Golovkin)
Police officers detain a man during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police clashed with demonstrators and have arrested some hundreds in central Moscow during a protest demanding that opposition candidates be allowed to run for the Moscow city council. (AP Photo/ Pavel Golovkin)
Police officers detain a man during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police clashed with demonstrators and have arrested some hundreds in central Moscow during a protest demanding that opposition candidates be allowed to run for the Moscow city council. (AP Photo/ Pavel Golovkin)