Spain's grid operator has countered a government report attributing April's Iberian Peninsula blackout to miscalculation of the energy mix.

Spanish authorities say the massive power outage in April across Spain and Portugal was due to technical and planning errors that led to a cascade of failures in the grid.

MADRID (Reuters) -Spanish grid operator Redeia will release its own report on the causes of the massive blackout that hit the Iberian peninsula on April 28, its chair, Beatriz Corredor, told a news briefing on Wednesday.