Domestic gasoline and diesel prices have risen for the ninth week, again reaching the highest levels this year. 

According to Opinet, a Web site on oil price information run by the Korea National Oil Corporation, the price of regular gasoline sold at gas stations nationwide rose by an average zero-point-nine won to one-thousand-620-point-three won per liter in the fifth week of August.

It's the highest level since December 2014 and nearly five percent up from the start of this year. 

The price of diesel also edged up to one-thousand-421 won and kerosene to over 948 won per liter in the last week of August. 

The National Oil Corporation said that concerns over escalating trade tension between the U.S. and China served to lower global oil costs while decreased inventory in the U.S. and Iran's threat to block the Strait of Hormuz over U.S. oil sanctions caused a rise in prices.

The corporation said domestic oil prices are expected to grow or remain steady.

The price of Dubai crude, which South Korea mainly imports, rose to an average 74-point-nine won per barrel in the fourth week of August, up two-point-six U.S. dollars from the previous week.