South Korean oil refiners have slumped on a worsening cracking margin this year, led by excessive diesel in stock due to sluggish demand at home and abroad amid a surplus of global supplies, data showed Monday.

According to the Korea National Oil Corporation, Korean oil refiners produced 152 million barrels in the first half of this year, up 3.7 percent from a year ago.

During the period, domestic diesel consumption edged up 1.2 percent to 70.4 billion barrels, less than half of the total diesel output.

The gap widened between supply and demand as Korean oil refiners improved production efficiency with advanced facilities, while failing to increase outbound shipments of leftover diesel in the face of competition from Chinese refiners and fuel subsidy cuts in emerging economies such as India and Indonesia. (Yonhap)