BBC news are now reporting that due to the 'conflict alert' system (STCA?) being off-line for maintenance, the procedures are for 2 controllers to man the sector (presumably as T & P). An extra set of eyes and ears to make up for the absence of the automated conflict alert, whether that be STCA or Medium Term Conflict Detection.
One of these controllers was reportedly on an "unauthorised break" when the accident happened.
The finger seems to be being pointed at the Russian crew. However, if, and it is only an 'if', both the aircraft were co-ordinated in at FL360, the controller has accepted a planning conflict that should be resolved by tactical means, i.e. vectoring or climb/descent, when on frequency. The fact that reports indicate instructions to change level were only given a minute prior to the accident occurring would suggest that 'avoiding action' was being instigated rather than a routine deconfliction of traffic. Vertical separation should of course be provided before the loss of lateral separation (presumably 5nm in the airspace concerned). Unfortunately, initial indications suggest that ATC error may be the root cause of the accident.