Several dozen nationalists camped in advance outside the Soviet-era building 10km south of central Odessa, which was heavily guarded by riot police and military units, following local reports that the activists had stripped the nearby pavements for projectiles, and began to assemble tires for barricades.

As the verdict was read out inside, a wall of attackers lined up against the police, who had locked their arms, in a bid to enter the building, and prevent the cleared men from being escorted out.

On command, the activists, charged at the human wall, releasing pepper spray into the officers’ faces, who replied with tear gas sprays of their own.

Dozens of journalists and bystanders present recorded the incident, while some tried to talk to persuade the protesters, many clad in military gear or wearing t-shirts with the Ukrainian trident – a symbol co-opted by far-right groups – to stop the attacks.

The pattern of clashes was repeated several times, and at one point an activist unloaded the contents of a fire hydrant into a riot policeman’s face.

“As always, the law enforcement officials keeping the peace became the ‘hostages’ of the ‘people’s fury.’ After lengthy skirmishes with the use of gas and other specialized means, the situation was brought under control,” wrote Ruslan Forostyak, the head of the regional national guard department, who said that several of the instigators have been charged with hooliganism.

‘No evidence of guilt’

May 2, 2014 was the culmination of months of clashes between the nationalist and “pro-Russian” factions in the Black Sea port, which resulted in at least 48 deaths.

The civil disorder began with a march by far-right football fans, proceeded to firearm exchanges and Molotov cocktail-throwing, and ended with a fire in a government building, where mostly anti-Kiev activists had been boxed in, where the majority perished.

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The accused, five of whom have been kept in detention, and two of whom are Russian citizens, each faced up to 15 years in jail.

But the judge dismissed the prosecutors’ case.

“There is no evidence to prove that the accused were guilty of the stated crimes. In fact, the prosecution did not even try to present any evidence,” he read out during the verdict, suggesting that the accused may have been doing nothing more than helping police maintain control.

The judge said that insufficient interviews had been conducted, some evidence had been collected illegally, and noted that although there was violence on both sides, only the pro-Russian activists were brought to face justice.

Upon their release, two participants were re-arrested, this time on charges of inciting separatism. Monday's trial pertained only to the street clashes on May 2, with separate proceedings still to come on responsibility for the fire.