“A few days before the terrorist attack in Russia, Tehran shared with Moscow information about a possible major terrorist attack in Russia, which was obtained from the interrogation of people arrested in connection with the deadly bombings in Iran,” one of the sources said.
A second source said Tehran’s briefing to Moscow about the impending attack did not include specific details about timing or the exact target.
“They (ISIS-K members) received instructions to prepare for a major operation in Russia… One of the terrorists (arrested in Iran) said that some members of the group had already left for Russia,” said the second source.
The United States also warned Russia in advance of a possible terrorist attack, but Moscow has publicly downplayed the information.
Iran’s foreign ministry and the Kremlin did not respond to requests for comment.
Russia’s FSB security service said four more people arrested on Sunday in connection with a foiled “terrorist” plot provided money and weapons for last month’s deadly attack on a Moscow concert hall.
More than 140 people were killed when gunmen stormed and set fire to the Crocus City Hall on March 22, the deadliest attack in Russia in two decades.
The FSB said in a statement on Monday that a day earlier in the southern region of Dagestan, it had arrested a group of four people who were “directly involved in the financing and provision of terrorist equipment to the perpetrators of the March 22 terrorist attack in Moscow’s Crocus City Hall.”
On Sunday, Russia’s National Anti-Terrorism Committee said it had arrested three people who were “planning to commit a series of terrorist crimes.”
The FSB said on Monday that four foreign nationals were arrested during an operation in the regional capital Makhachkala and the nearby city of Caspian.
The Interfax news agency quoted an FSB video showing one of the detained men saying: “I delivered weapons to them, to those guys who attacked Crocus City Hall.” I brought them weapons from Makhachkala.”
Russian authorities earlier announced the arrest of 12 people they said were connected to the attack, including four suspected gunmen who were identified as Tajik nationals.
Islamic State (IS) has claimed responsibility for the massacre, which it says is the worst on European soil, although President Vladimir Putin has spoken of Ukraine’s links with the West.
Kyiv and the West have repeatedly denied any involvement and accused Moscow of “taking advantage” of the tragedy.
Dagestan is a Muslim-majority region in Russia’s southern Caucasus.
The FSB has been criticized for failing to prevent the attack, despite the US intelligence community privately and publicly warning that “extremists” were planning an attack at “large gatherings” in Moscow.
The agency regularly announces that it is busting alleged “terrorist groups,” but in recent months it has mostly announced the arrests of what it says are pro-Ukrainian saboteurs who were plotting attacks on Russian military facilities and infrastructure.
