South Korean refiners such as S-Oil Corp. have racked up decent profits in the first half of the year, driven by their better-than-expected sales and relatively high cracking margins, industry data showed on Monday.

According to the data compiled by market researcher CEO Score, S-Oil, the country's third-largest oil refiner, posted the highest operating income to sales ratio of 14.9 percent among companies affiliated with the top 30 conglomerates in terms of sales.

S-Oil logged an operating income of 1.13 trillion won ($1 billion) in the first half, up 34.1 percent from a year earlier, with its operating income to sales ratio soaring up 6 percentage points over the cited period, the data showed.

SK Innovation Co., the country's top refiner, came in fourth in terms of the operating income-to-sales ratio with 9.4 percent, trailed by GS Caltex Corp. with a 9.3 percent ratio.

SK Innovation logged an operating income of 1.12 trillion won in the second quarter, the second-biggest on a quarterly basis. GS Caltex also posted an operating income of 766 billion won during the April-June period, up 13.4 percent from a year earlier.

Meanwhile, the data showed that the country's top 30 business groups suffered a 3.3-percent on-year decline in their first-half sales to 545.76 trillion won, while seeing a 9.7-percent rise in their operating income at 34.88 trillion won. (Yonhap)