MOSCOW -- Aleksandr Vorobyov, who worked as an assistant to President Vladimir Putin's envoy to the Urals region, has been sentenced to 12 1/2 years in prison on a charge of high treason.

A Moscow court sentenced Vorobyov on April 14 after a trial that was held behind closed doors due to classified materials in the case.

Vorobyov was detained in July 2019 and fired shortly after the arrest.

His chief, Nikolai Tsukanov, left the post of presidential envoy in the Ural Federal District more than a year after Vorobyov was charged with high treason.

At the time, Tsukanov was a member of Russia's Security Council, the State Border Commission, and the Presidential Council on Priority Projects. He quit those posts after his aide's arrest.

Media reports at the time said that investigators had found a Polish passport and a recording device in Vorobyov's possession at the time of his arrest.

Vorobyov was stripped of the rank of state councilor of the third degree, which corresponds to the military rank of major general, and expelled from the ruling United Russia party.

The affair was the first publicly known case of a government official being arrested on suspicions of treason in post-Soviet Russia.

Since then, the number of cases of alleged high treason in general has increased dramatically in Russia.

One of the latest high-profile high treason cases involves Ivan Safronov, a journalist and an aide to the Russian Roskosmos space agency chief, Dmitry Rogozin.

Safronov was arrested on July 7 and later charged with passing classified material to the Czech Republic. He has denied the charge.