According to a UK newspaper, the European Commission has written to the Spanish government in the strongest possible terms in a bid to push through E.ON's acquisition of Endesa.

The Daily Telegraph reports that the commission has been unprecedented in its condemnation of Spain’s attempts to effectively derail the E.ON-Endesa merger through its energy regulator imposing a plethora of conditions.

The regulator was working to new guidelines laid down earlier this year by socialist premier Jose Luis Rodriguez Zapatero, which were aimed at protecting companies of national strategic importance from foreign takeover.

Under the regulatory ruling, E.ON would have to divest around a third of Endesa’s current Spanish generating capacity, including a nuclear station. Even Endesa feels these terms are too onerous, and is apparently poised to appeal the decision itself.