Russian security forces on Thursday have arrested four men linked to the Islamic State (ISIS) terror network and suspected of planning a series of terror attacks on Moscow's transport system.
'They were preparing terrorist attacks on Moscow transport infrastructure using improvised explosive devices, ' according to Russia Today, adding that they were ISIS militants.
The FSB said that the suspects' activities had been directed from Syria.
The detainees were holders of Russian and Central Asian passports, and they received instructions from the Islamic State (IS) terrorist group operating in Syria, the FSB said in a statement.
The agency said in a statement that the four were working under directions from IS in Syria to prepare attacks using self-made explosive devices.
"The terrorists planned after committing a terrorist act to go to Syria to participate in combat operations as part of Islamic State worldwide terrorist group", the message reads. Searching the site, the officers also found components of improvised explosive devices, a Kalashnikov AK-74 assault rifle, a PM handgun, and ammunition.
He said the FSB needed to improve work aimed at preventing such incidents as the April 3 terrorist attack in Russia's second largest city of St. Petersburg, which killed 14 people and injured dozens of others. Eleven people remain in custody over case, the Russian Investigative Committee reported earlier in May.