Vladimir Putin has held another phone call with Tajik President Emomali Rahmon in the wake of the concert hall attack.
All four men suspected of carrying out the massacre have been identified as Tajik nationals by Russian media.
According to Russia's foreign ministry, Mr Rahmon said today there "could not be any justification" for the attack.
In a previous phone call, the Tajik president condemned the "terrorist attack" and told Mr Putin that "terrorists have no nationality, no homeland and no religion," Mr Rahmon's office said in a statement.