About 1,500 people in Moscow have demonstrated against police abuse of power in the wake of a prominent Russian journalist's arrest on drug-dealing charges that the government admitted days later had no basis.

Organizers had official permission for Sunday's protest rally, unlike one supporters of investigative reporter Ivan Golunov held last week. An arrests-monitoring group says police detained about 400 people at the unauthorized rally.

Russian journalists and rights activists claimed before and after Golunov's June 6 arrest that he was set up. They alleged Moscow police officers planted drugs on the journalist. Golunov's lawyer says he was beaten in custody.

Demonstrators gather to attend a rally titled "Law and justice for all" in support of all journalists in Moscow, Russia, Sunday, June 16, 2019. (AP PhotoPavel Golovkin)

Demonstrators gather to attend a rally titled "Law and justice for all" in support of all journalists in Moscow, Russia, Sunday, June 16, 2019. (AP PhotoPavel Golovkin)

Russian authorities took the rare step Tuesday of saying the charges were a mistake and had been dropped.

President Vladimir Putin subsequently fired two senior police officials.

Demonstrators applaud an orator as they gather to attend a rally titled "law and justice for all" in support of all journalists in Moscow, Russia, Sunday, June 16, 2019. (AP PhotoAlexander Zemlianichenko)

Demonstrators applaud an orator as they gather to attend a rally titled "law and justice for all" in support of all journalists in Moscow, Russia, Sunday, June 16, 2019. (AP PhotoAlexander Zemlianichenko)