A terrorist plot targeting Moscow’s public transport has been foiled by Russian police after a raid on a Moscow apartment on Sunday revealed a home-made bomb containing around 11 pounds of explosives. Russia’s Federal Security Service has confirmed that some of the 15 men arrested in connection with the plot were trained in Isis camps in Syria.

“There was a set address in Moscow where between six and 11 people periodically stayed, some of who participated in Isis military training camps in Syria,” an FSB spokesperson told Russian news agency Interfax. “They arrived back in Russia long before the start of Russia’s military operation [in Syria].” He added that during the interrogation of two detainees, it “quickly became apparent that they planned to carry out a terrorist attack on public transport in Moscow”.

Three detained on suspicion of planning Moscow bombing

Security forces evacuated over 120 residents from the apartment block on Sunday and cut the off gas supply to the building while arrests were made and the bomb defused.

One official compared the size of the bomb to that detonated at last week’s peace rally in Ankara, adding that the difference between the two devices lay in the fact that the explosive found in Moscow “would have been detonated with a mobile phone”.

Ankara explosions - in pictures Show all 15 1 /15 Ankara explosions - in pictures Ankara explosions - in pictures Ankara attack Ankara explosions - in pictures Ankara attack Ankara explosions - in pictures Ankara attack Ankara explosions - in pictures Ankara attack Ankara explosions - in pictures Ankara attack Ankara explosions - in pictures Ankara attack Ankara explosions - in pictures Ankara attack Victims lie on the street as the scene of the explosion is cordoned off following an explosion at the main train station in Turkey's capital Ankara, on October 10, 2015. AFP/Getty Images Ankara explosions - in pictures Ankara attack An injured man holds another casualty after the blasts in Ankara Reuters Ankara explosions - in pictures Ankara attack An injured woman being helped following the explosion on Saturday morning. AFP/Getty Images Ankara explosions - in pictures Ankara attack An injured person is comforted as she lies on a rally banner following an explosion at the main train station in Turkey's capital Ankara, on October 10, 2015. AFP/Getty Images Ankara explosions - in pictures Ankara attack Bodies of victims are covered with flags and banners as police officers secure the area after an explosion in Ankara, Turkey, Saturday, Oct. 10, 2015. AP Ankara explosions - in pictures Ankara attack Blood covered flags are seen at the blast scene after an explosion during a peace march in Ankara, October 10, 2015 Turkey. Getty Images Ankara explosions - in pictures Ankara attack An injured person is lifted away using a rally banner following an explosion at the main train station in Turkey's capital Ankara, on October 10, 2015. AFP/Getty Images Ankara explosions - in pictures Ankara attack Victims at the blast scene after an explosion during a peace march in Ankara, October 10, 2015 in Ankara, Turkey Getty Images Ankara explosions - in pictures Ankara attack Paramedics and police work outside Ankara Central Station after multiple explosions in Turkey, 10 October 2015. EPA

Since the beginning of Russia’s airstrikes in Syria last month, observers have expressed fears that Russia could be leaving itself open to revenge attacks. Last week, Pentagon chief Ashton Carter told a meeting of Nato defence ministers that Russia would pay the price for using its forces to prop up Bashar al-Assad’s regime, adding that “this will have consequences for Russia itself, which is rightfully fearful of attacks on Russia”.

Russia’s military intervention in Syria has been strongly criticised by western leaders, who accuse Moscow’s airstrikes of targeting the opposition to Bashar al-Assad’s regime in a bid to help the Syrian president stay in power.