ARMYANSK, Ukraine -- A court in Russia-controlled Crimea has postponed a preliminary hearing in absentia against a veteran Crimean Tatar leader and prominent Soviet-era dissident who has vehemently opposed Russia's illegal annexation of the peninsula from Ukraine in 2014.

The court in the Crimean city of Armyansk was scheduled to start the hearing for Mustafa Dzhemilev on June 25, but postponed it after it turned out that neither the defendant, nor his legal team, had received official papers from prosecutors, Dzhemilev's lawyer, Nikolai Polozov, said.

"The defense is not aware of the essence of the accusations, which witnesses the prosecuting side plans to summon to the trial, nor what evidence will be presented in the courtroom. Under these circumstances, it is impossible to start the process," Polozov said.

Russia's Investigative Committee said in April that it had launched a probe against the 76-year-old member of the Ukrainian parliament on charges of "illegally crossing the Russian border, the careless storage of a firearm that led to serious consequences, and the illegal possession of ammunition."

Ukraine's presidential representative office in Crimea has condemned the move by the Investigative Committee, calling it politically motivated.

Dzhemilev was the chairman of the Crimean Tatar's self-governing assembly -- the Mejlis -- until it was banned by pro-Moscow representatives in Crimea.

Dzhemilev was a leading human rights activist during the Soviet era and served six jail sentences in Soviet prison camps from 1966 to 1986.

He is also known for going on a 303-day hunger strike -- the longest in the history of the Soviet human rights movement.

Dzhemilev has been banned from Crimea since Russia occupied and seized control of the peninsula.

Rights groups and Western governments have denounced what they call a campaign of oppression targeting members of the Turkic-speaking Crimean Tatar minority and others who opposed Moscow's rule.

The majority of Crimean Tatars opposed the Russian takeover of their historic homeland.