European competition regulators on Thursday stepped up their threat to take Spain to the European courts over the country's refusal to drop conditions placed on the €42.5bn ($66bn, £34bn) takeover of Endesa, the energy group, by Italy's Enel and Spain's Acciona.

The European Commission sent a formal request – or “reasoned opinion” – to Spain, thus triggering a one-month reply period, after which Spain could be referred to the European Court of Justice.