"The windfarms are of outstanding quality with superb load factors and favourable regulatory regimes," it said.

The investment comes amid increasing economic and political pressure on utilities to lower emissions of carbon dioxide, a gas most blamed for causing global warming. E.ON plans to invest 3 billion euros in renewable energies by 2010, 5 percent of its total investments of 60 billion euros envisaged for the period.

E.ON is taking on 256 million euros of debt as part of the deal, which also include smaller hydropower and biomass plants. The company operating the assets is called Energi E2 Renovables Ibericas.

State-owned Dong is shedding the windparks ahead of its listing on the stock exchange. Denmark is due to sell part of its stake in the utility and list the firm on the Nordic OMX exchange in the second half of the year, but plans to retain a majority stake.

Analysts have put the total value of the company at somewhere between 70 billion and 80 billion Danish crowns ($14.83 billion).