Law-enforcement authorities pressed on Monday criminal charges against four opposition politicians arrested for organizing an anti-government demonstration in Yerevan that was broken up by riot police.

Three of them -- Armen Martirosian, Hovsep Khurshudian and Davit Sanasarian -- are senior members of Zharangutyun (Heritage), a major opposition headed by Raffi Hovannisian. The fourth man, Andrias Ghukasian, is a former presidential candidate.

The four men were part of an ad hoc opposition body that organized demonstrations in support of anti-government gunmen that seized a police compound in Yerevan’s Erebuni district on July 17 to demand President Serzh Sarkisian’s resignation.

They were taken into custody after leading late on Friday more than 1,000 protesters to Yerevan’s Sari Tagh neighborhood adjacent to the compound. Riot police used tear gas and stun grenades to disperse the crowd after the organizers ignored their warnings to march back to the city center. Senior police officers said that they gathered too close to the compound besieged by security forces.

More than 60 people, most of them protesters, were seriously injured and hospitalized in the ensuing crackdown. The Armenian opposition, human rights groups as well as the U.S. Embassy in Yerevan accused the police of using excessive force.

Despite that criticism, the four politicians were formally charged with organizing “mass disturbances.” All of them denied the allegations as politically motivated through their lawyers.

Martirosian’s lawyer, Givi Hovannisian, said his client was detained while negotiating with senior law-enforcement officers at the scene moments before the riot police charged at the protesters. “This is political persecution,” Hovannisian told RFE/RL’s Armenian service (Azatutyun.am).

Unlike Martirosian, Sanasarian was arrested early on Saturday in Yerevan’s Surb Grigor Lusavorich hospital where he was receiving medical aid. Sanasarian fainted while being dragged away by several plainclothes officers.

Ghukasian, meanwhile, was reported to have gone on hunger strike on Monday as he attended a court hearing on his pre-trial arrest sought by investigators.