The independent Russian newspaper Novaya Gazeta received an envelope containing an unidentified white powder on April 19, the newspaper reported.

The envelope's only return address was "Grozny," the capital of Chechnya, where preachers and political officials have recently threatened the newspaper for reporting on the alleged torture and detention of men believed to be gay, according to the newspaper and the Committee to Protect Journalists.

The press-freedom watchdog called on Russian authorities to swiftly bring to justice those responsible for the threat.

"The continuing threats against Novaya Gazeta and its journalists require immediate attention and action from both Russia's federal security agencies and the Kremlin," the committee's Europe and Central Asia Program Coordinator Nina Ognianova said.

"We call on Russian security agencies to do everything possible to catch and punish those responsible for this sickening campaign to silence a brave, independent newspaper," she added.