"About 20 armed men from the FSB (security service) came to my house at 5:30 am and seized all documents, computers and telephones," said Lilia Budzhurova, the deputy director of ATR channel, adding that her lawyer was not allowed to be present.
The FSB said in a statement distributed via Russian news agencies that the probe had been launched on October 22 against Lenur Islyamov, who owns the channel and other assets in Crimea.
The police actions are related to an "extremism" probe launched against Islyamov, Budzhurova added.
Crimea region leader Sergei Aksyonov, who became governor of the Black Sea region after the peninsula was annexed from Ukraine in March 2014, had long criticised the channel for being anti-Russian, though the outlet had significantly toned down its political coverage.
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However authorities are accusing Islyamov of stoking unrest by organising a blockade of roads from mainland Ukraine to Crimea to stop the flow of supplies in protest of violations of rights of Crimean Tatars, an indigenous ethnic group on the peninsula that makes up about 13 percent of its population.
His office added that police will "look into every organiser of subversive actions against Russia and Crimea."
Islyamov, who had Russian citizenship even before the peninsula was annexed, was a moderate supporter of cooperation with the new authorities early on in Crimea's crisis last year, when many Crimean Tatars were vehemently opposed to Russia's authority on the peninsula.
Besides the channel, he owns several other firms in Crimea, including a transportation company and a distributor of Apple products, according to the governor's office.