Danish oil and gas giant DONG has offered to buy 40% of national utility Elsam at the same price offered by Swedish rival Vattenfall, raising the spectre of a drawn out bidding war. DONG, which already owns 24% of Elsam, made the offer in an attempt to keep the proposed merger of the two companies in play. However, Vattenfall has already gained control of more than 35% of Elsam from a shareholder consortium that represents 67% of the capital in Elsam.