Video footage shows two police officers assaulting David Frenkel and knocking him to the floor after a brief discussion. Doctors diagnosed Frenkel with a fractured arm after the incident.
Mediazona, the media for which Frenkel works, said the officers tried to kick him out of the venue. The journalist had arrived after an election monitor complained that they were being forced out.
RUJ President, Vladimir Solovyov, condemned the attack against the journalist and said such actions are "unacceptable." The union also offered Frenkel legal assistance.
According to media reports, a spokesman for President Vladimir Putin, Dmitry Peskov said the attack should be "thoroughly checked and investigated." Commissioner for Human Rights in Russia Tatyana Moskalkova also demanded an investigation of the incident.
IFJ General Secretary, Anthony Bellanger, said: "Police brutality against journalists who are merely doing their job is unacceptable. We stand in solidarity with David and urge the authorities to investigate the incident. Attacks on journalists can't go unpunished".