He said the company had made an attractive offer, "not just from a financial perspective".
"We believe that Endesa's business prospects as part of E.ON are very good."
E.ON received earlier this week a credit line of 32 billion euros ($68.3 billion) to finance the planned takeover, which would result in the largest acquisition in the energy sector if successful.
But the Spanish government has tried to block the deal following the announcement by the domestic firm Gas Natural that it will raise its bid to squeeze E.ON out. Gas Natural had offered 22.5 billion euros (48 billion dollars) to take over Endesa, whichis Spain's major electricity supplier.




