The extremism charge could place the reporter Mykola Semena in prison for five years. His two lawyers, Emil Kurbedinov and Andrey Sabinin, said that Semena was formally charged on Wednesday, following a months-long investigation.

Semena works for a local website of Radio Free Europe in Crimea and opposes the Russian annexation.

The local branch of the Russian security service FSB launched an investigation into the 66-year-old reporter over the article titled "Blockade – necessary first step towards liberating Crimea." The comment expressed support for a plan to cut off supplies - including food - from the Ukrainian mainland to the peninsula.

"Hunger is not the issue. This is an issue of life and death," the article says, which investigators claim was written by Semena under a pseudonym. "The issue is – Motherland or death! Today is not just a slogan, it's reality."

Illegal to question Russian borders

The authorities searched Semena's house, confiscated his equipment and briefly detained the journalist in April.

"The author of the text has made statements (…) inciting measures of isolations, including combat operations," the prosecutors said in a statement. He was also accused of justifying "sabotage and extremism" in his articles.

Authorities forbade Semena from leaving the regional capital Simferopol.

US embassies in both Ukraine and Russia, as well as international organizations protecting journalists, decried the investigation against Semena.

Shorty after the referendum which formalized the Russian annexation of Crimea in March 2014, Russian parliament passed a law forbidding the questioning of Russia's territorial integrity. Observers fear that the bill is now used to silence dissent.

dj/kms (AP, Interfax)