Ministers agreed on the proposed legislation to try to curb energy spending that has grown over the years because of rising subsidies, Deputy Prime Minister Soraya Saenz de Santamaria told reporters.

"The cabinet approved an important reform to tackle the deficit, which is the difference between the cost of production and what we get from its sale," she said.

"It is one of the most necessary reforms because the debt left by previous governments is now 24 billion euros and, if we don't put the brakes on, it could rise by more than five billion euros each year."