This will bring the total quotas issued this year to 151 million tonnes of crude oil, or roughly 3.02 million barrels per day (bpd).

The amount is equivalent to about 30% of China's total crude oil imports in the first five months of this year at 9.91 million bpd as reported by official customs data.

Of the new issues, private refiner and chemical giant Hengli Petrochemical Co Ltd won 12.8 million tonnes, the largest recipient among a total of 43 refiners.

Thirty-three of these plants are independent oil processors based in the eastern province of Shandong. State-run ChemChina and provincial government-backed Shaanxi Yanchang Petroleum Group are among the rest.

(Reporting by Florence Tan and Chen Aizhu; editing by Christian Schmollinger and Emelia Sithole-Matarise)