Human rights advocates and European lawmakers are calling on Russia to drop criminal charges against Mykola Semena, an RFE/RL contributor who is accused of separatism in a case supporters say is aimed at silencing criticism of Moscow's seizure of Crimea from Ukraine.

Semena was given a final version of the charges in December and was served on January 20 with the closing indictment in his case, a detailed document that includes descriptions of evidence, the names of prosecution witnesses, and other information.

The development means that Semena, who is being prosecuted over an article expressing the view that Crimea should be returned to Ukraine, could be tried soon.

Semena was detained in April and then released but ordered not to leave the peninsula. He could be sentenced to five years in prison if convicted.

The Paris-based group Reporters Without Borders (RSF) urged Russian authorities on January 26 to drop the "absurd" charges against Semena, saying he “simply expressed his opinion on the annexation of Crimea."

"In no way should he be prosecuted for that," Johann Bihr, the head of RSF’s Eastern Europe and Central Asia desk, told RFE/RL. He said that Semena’s case was "more proof of the suppression of freedom of expression in Crimea since the Russian annexation."

"Nearly all independent media on the peninsula have been suppressed," Bihr said. "All the media which kept a pro-Ukrainian editorial line were shut down or forced to leave the peninsula and move to Kyiv."

In a resolution adopted on January 24, the Parliamentary Assembly of the Council of Europe (PACE) called on Russia to drop its charges against Semena and two other journalists it said were being prosecuted "for their reports about the illegal occupation and annexation of the Crimean Peninsula by the Russian Federation."

Also on January 24, the Organization for Security and Cooperation in Europe's (OSCE) media-freedom representative, Dunja Mijatovic, expressed concern about what her office called the "persecution" of Semena, a contributor to RFE/RL's Crimea Realities website.

"The case of Semena reminds us all of the arbitrary practice of silencing critical voices in Crimea," Mijatovic said. "It is totally unacceptable to persecute the journalist for expressing his views. I call for all charges against Semena to be dropped."

On January 25, RFE/RL President Thomas Kent said that the charges against Semena were "part of a concerted effort by Russian and Russian-backed authorities to obstruct RFE/RL's journalistic mission to provide an independent press to residents of Crimea."

Russia seized control of Crimea from Ukraine in March 2014, after sending in troops to secure key facilities and staging a referendum dismissed as illegitimate by Ukraine, the United States, and a total of 100 countries in the UN General Assembly.

Human rights advocates say Russian and the authorities it imposed in Crimea have conducted a persistent campaign of oppression targeting opponents of the annexation, including many members of the Crimean Tatar minority, as well as independent media outlets and journalists.

A lawyer for Semena, Emil Kuberdinov -- who is a Crimean Tatar -- was detained and questioned in the regional capital, Simferopol, on January 26 on suspicion of "distributing extremist material," according to a colleague, Edem Semedlyayev.

He said that police searched Kuberdinov's office and confiscated his computer.

The detention came as the Russian-imposed authorities said security forces were searching for alleged members of Hizb ut-Tahrir, an Islamic group that is banned in Russia, in a "special operation" in the nearby town of Bakhchisaray.