The request comes after a nationwide power outage in April that revived debate over Spain's decision to close all of its nuclear reactors by 2035.

Spanish energy firms Endesa, Iberdrola and Naturgy sent a letter to the ecological transition ministry to declare their "availability" to extend the closure deadline of the Almaraz nuclear plant, a ministry source told AFP.

The plant in western Spain contributes around seven percent of Spain's total electricity production.

Socialist Prime Minister Pedro Sanchez's government has bet heavily on renewable energy, which he says led to a 50 percent drop in electricity prices since coming to office in 2018.

Leveraging its sunny plains, windy hillsides and fast-flowing rivers, Spain intends to raise the share of renewable-generated electricity to 81 percent of its total by 2030, up from about 50 percent now.

Critics warn that renewable energy can be unpredictable and less reliable, and say nuclear power can provide a steady backup.

The government source said any decision to extend the life of the Almaraz plant would require compliance with safety standards and no additional costs for consumers.

Contacted by AFP, the three power companies that own the Almaraz plant did not immediately comment.

Spain currently has five nuclear plants, down from eight in the 1980s.

The remaining plants, comprising seven reactors, account for 19 percent of Spain's electricity mix, down from 38 percent four decades ago.

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ENDESA

IBERDROLA

Naturgy