Russian intelligence officers have searched the office of Russia's most prominent independent radio station in connection with an extremism probe.

Alexei Venediktov, editor-in-chief of Ekho Moskvy, said Tuesday that FSB officers arrived at the station's premises in central Moscow and searched the computer servers for correspondence with Andrei Piontkovsky, who writes a blog for Ekho. Venediktov said the editor-in-chief of Ekho's website has been summoned for questioning in connection with the probe.

The FSB's press office did not name Piontkovsky but said it was investigating calls to violate the country's territorial integrity, a criminal offense in Russia.

Piontkovsky was reported to have left the country in February, when prosecutors started looking into his blog post discussing the future of the southern republic of Chechnya.