MOSCOW, December 28 - RAPSI. The investigation into the case against 12 suspected participants in violent unrest during opposition rally in Moscow on May 6 has been completed, Investigative Committee spokesperson Vladimir Markin said on Friday.

"Investigative procedures concerning 12 people have been completed. The suspects' attorneys have started studying the case materials. Then the case will be transferred to the Prosecutor General's Office for a decision on whether it should be submitted to court," Markin said.

The protest rally was held on May 6 in Bolotnaya Square in central Moscow, following the election of Vladimir Putin to his third presidential term.

Although authorized, the opposition rally across Moscow led to clashes with the police. Dozens of protesters and police officers were injured. The police detained over 400 rally participants.

After May 6, the opposition continued its protests in the form of "people's promenades," wherein crowds of opposition activists walked peacefully together through the city.

One of those arrested over the May 6 rally, Maksim Luzyanin, was sentenced to 4.5 years in prison.

On June 5, the State Duma, Russia's lower house of parliament, passed a bill increasing fines for violating rally procedures and the upper house approved it the following day.

The bill was then signed into law by President Vladimir Putin.

The law has increased the fines by 10 times, stipulated compulsory community service for violators and prohibited wearing of masks during protests. The maximum fine has risen to 300,000 rubles ($9,200) for individuals and 600,000 rubles ($18,400) for public officials.

The law also cracks down on unauthorized rallies by prohibiting any mass events organized under the guise of public gatherings, or so-called "people's promenades," should they cause public unrest.