Islamic State has released a video threatening attacks in Russia "very soon" in revenge for Russian bombing in Syria, the SITE monitoring group said on Thursday, and the Kremlin said Russian state security services would study the material.
Al-Hayat Media Center, the militant group's foreign language media division, released a video in Russian with chants of "Soon, very soon, the blood will spill like an ocean", SITE reported.
Islamic State has previously called for attacks on Russia and the United States in revenge for strikes by their warplanes on its fighters in Syria.
Western intelligence officials suspect the ultra-hardline Sunni group of planting a bomb in a Russian passenger plane which crashed in Egypt's Sinai Peninsula on 31 October, killing all 224 passengers and crew.
Islamic State militants fighting Egyptian security forces in Sinai said they brought down the plane which was taking Russian tourists back home from the Egyptian tourist resort of Sharm al-Sheikh.
Russia's security agencies will undoubtedly look into a video, Kremlin spokesman Dmitry Peskov said on Thursday.
"I do not know the authenticity of this video, I do not know the authenticity of these sources, but in any case no doubt this will be material for review by our special (security) services," Peskov told journalists on a conference call.
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