SINGAPORE/BEIJING, June 14 (Reuters) - China has issued a third batch of 2023 crude oil import quotas, raising the total volume in the first half of this year to 194.1 million tonnes, up 20% from the same period last year.

Thirty-three companies, mostly independent refiners, are receiving 62.28 million tonnes of allotments in this round, according to six sources with knowledge of the matter and documents reviewed by Reuters on Wednesday.

That compares to 52.69 million tonnes issued by Beijing in June last year and a total released quota of 161.72 million tonnes over the first half of 2022.

Zhejiang Petroleum & Chemical Coa subsidiary of Rongsheng Petrochemical, was granted 20.0 million tonnes in the new round of issuance. Hengli Petrochemical and Shenghong Petrochemical received 3.0 million tonnes and 8.0 million tonnes, respectively.

The rest of quotas were allotted to smaller-sized independent refiners, known as teapots, in the eastern Chinese province Shandong.

Chinese independent refineries have been boosting imports of discounted crude oil essentially from Russia, Iran and Venezuela over the past months to improve refining margins amid lacklustre fuel and petrochemical demand in the country.

Analysts estimate that refining margins at teapot refineries are more than double the level than at their state-backed counterparts.

The flood of discounted feedstock prompted Chinese authorities to toughen scrutiny of crude oil quotas. (Reporting by Andrew Hayley in Beijing and Muyu Xu, Aizhu Chen and Florence Tan in Singapore; Editing by Muralikumar Anantharaman and Sonali Paul)