Paris - French utility giant EDF has taken on US billionaire Warren Buffett over US energy supplier Constellation Energy Group, the online edition of the daily Le Figaro reported on Wednesday.

According to the report, EDF has offered to purchase half of Constellation's nuclear energy activities for 4.5 billion euros (5.7 billion dollars).

The bid values Constellation at 52 dollars per share. That is almost double the offer by Buffett's MidAmerican Energy of 4.7 billion for the entire firm.

EDF said that it hoped to wrap up the operation within six to nine months after approval by US authorities.

The decision on which offer to accept could come on December 23, when Constellation shareholders gather for a general meeting.

Investors reacted sceptically to the offer and bid down EDF shares by more than 6 per cent in early trading on the Paris Bourse. (dpa)