On March 22, gunmen opened fire at the Crocus City concert hall near Moscow, setting the venue alight and wounding 80 people.

Moscow has detained 12 people and charged eight with "terror-related offences" over their alleged roles in the attack. They include four suspects from Tajikistan who are accused of carrying it out, Russian state media said.

IS swiftly claimed the attack, although Moscow has said repeatedly that the attackers had links to "Ukrainian nationalists" -- a claim Kyiv rejects.

In the latest issue of its weekly Al-Nabaa magazine published Friday on Telegram channels, the group said its fighters had been hunted down by ground and air forces.

The operation ended when the men were surrounded in "a forest", ISIS said, adding that they were now in "captivity".

A Moscow court has remanded the four main suspects in custody until May 22 -- a date likely to be extended until their trial.

Russia has been a repeated target of attack by ISIS, in retaliation for its suppression of unrest in Muslim-majority regions and its support for President Bashar al-Assad's government in the civil war in Syria.