Pro-Russian separatist leader Igor Strelkov has resigned, the rebel group Donetsk Republic said on its website.
It said Vladimir Kononov would replace Strelkov as the new military commander.
Strelkov's resignation is the third change at top of the rebel leadership in the past week.
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The band announced at a free concert on Friday that they would take over the event's Pyramid stage on Saturday June 25.
The victims were collecting permits and escorts a day after their home town was liberated from the extremists.
Scotland Yard said the male youths will appear in custody at Westminster Magistrates' Court on Saturday.