Russia’s top security agency said it has broken up a terrorist cell whose members provided weapons and cash to suspected attackers of a Moscow concert hall.

The Federal Security Service, or FSB, said it detained four suspected members of the cell in the southern Russian province of Dagestan in the North Caucasus.

The agency alleged that the suspects were involved in channelling funds and providing weapons to the gunmen who attacked the concert hall on Moscow’s western edge on March 22, killing 144 people in the deadliest attack on Russian soil in two decades.

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A woman sprinkles flowers at a makeshift memorial during a vigil for the victims of the Moscow concert hall attack (Dita Alangkara/AP)

“The detained militants directly participated in financing the perpetrators of the March 22 terror attack on the Crocus City Hall in Moscow and providing them with terror means,” the FSB said in a statement.

It said one of the suspects detained in Dagestan confessed to taking weapons to the Moscow attackers.

The FSB released a video showing one of the suspects saying that they also planned an attack in the city of Kaspiysk in Dagestan.

The agency said the suspects are foreign nationals, without specifying their nationality. The suspected attackers of the Moscow concert hall arrested hours after the March 22 raid are citizens of the Central Asian nation of Tajikistan.

The detention of four suspects in Dagestan follows the arrest of the four suspected gunmen and seven others who were accused of involvement in the attack.

An affiliate of the so-called Islamic State group claimed responsibility for the attack.

President Vladimir Putin acknowledged that “radical Islamists” conducted the raid but alleged – without providing evidence – that Ukraine and the West were involved, despite Kyiv’s vehement denials.