Japan's antitrust watchdog on Thursday ordered three major utilities to pay a total of ¥101 billion ($763 million) in fines for forming cartels over electricity sales in a move that goes against the nation's efforts to free up the electric power market.

The penalty is the highest ever imposed by the Fair Trade Commission for a violation of the anti-monopoly law.

Chugoku Electric Power was slapped with about ¥70.7 billion in surcharges, Chubu Electric Power and its subsidiary with about ¥27.56 billion and Kyushu Electric Power with about ¥2.76 billion, the commission said.