MOSCOW -- An independent investigation has blamed the Russian authorities and police for the violence that erupted at an opposition protest on Moscow's Bolotnaya Square last year.
The investigative commission, composed of leading public figures and rights advocates, released its findings late on April 22 at a public event in Moscow.
The report blames riot police for "excessive use of force" against demonstrators on May 6, 2012, resulting in numerous injuries.
Authorities have only recognized injuries sustained by police officers.
More than 20 demonstrators have been charged with participating in "mass unrest" and assaulting police.
Fifteen remain in pretrial detention and four are under house arrest. All face prison if convicted.
Georgy Satarov, the head of the INDEM think tank in Moscow and a former aide to Russia's first president, Boris Yeltsin, co-authored the report.
He told RFE/RL that the demonstrators' reactions were understandable.
"They defended themselves and they defended others. Many of those who were not arrested and are now free would have done the same," Satarov said.
The report says riot-police officers beat up "helpless, unarmed people," including women and elderly people.
It blames police for deliberately creating bottlenecks by blocking the protesters' path, contributing to tensions.
It also accuses the authorities of sending a "significant number of provocateurs" into the crowd to spark clashes -- a claim backed by witnesses as well as the Kremlin's human rights council.
Satarov said the pieces of asphalt that some the defendants are accused of throwing at police had been placed on the square ahead of the rally.
"Bolotnaya Square was cordoned off overnight, it was surrounded by a tight fence inside which the asphalt was cut into pieces," Satarov said.
"This circumstance was fully used by provocateurs. There are a multitude of other signs that indicate a planned provocation by authorities."
One of the defendants in the so-called Bolotnaya case, Maksim Luzyanin, has already been sentenced to 4 1/2 years in prison after pleading guilty and cooperating with investigators.
Authorities say their probe into the other defendants is nearing completion.
Investigators are still tracking down some 70 other protesters they suspect of disruptive behavior at the rally.
The investigative commission plans to send its report to the Organization for Security and Cooperation in Europe, the European Parliament, and the United Nations.
It was formed by the opposition party RPR-PARNAS, the December 12 Roundtable civil group, and the May 6 Committee. It includes top rights activists like Lyudmila Alekseyeva and a number of prominent public figures such as economist and former Economy Minister Yevgeny Yasin.
With reporting by Interfax and ITAR-TASS