Klesch agreed in July to buy the 135,000 barrels per day refinery from Murphy Oil for an undisclosed sum and said the struggling plant would restart operations.

It refines gasoline, diesel, fuel oil, jet fuel, LPG and propylene, as does the Heide Refinery in Germany, also owned by the Klesch Group.

But the European Commission, the EU executive, concluded there would be no antitrust concerns as any overlap was limited and the Milford Haven refinery would face strong competition from other players.

The European refining industry has suffered from years of negative profit margins and faces competition from a surge of U.S. products following the U.S. shale boom.

Some players, however, have seen opportunities to snap up struggling refineries.

(Reporting by Barbara Lewis in Brussels and Ron Bousso in London; Editing by David Holmes)