China's Sinopec Corp is restarting its 100,000-barrel-per-day (bpd) Zhanjiang Dongxing refinery after a shutdown of nearly a month, an industry official with direct knowledge of the matter said on Wednesday.

Sinopec ordered in late September the closure of three subsidiary plants in the southern province of Guangdong, including Dongxing and Guangzhou, after state media said they had violated environmental rules.

"The refinery is restarting after passing environmental checks and winning approval from Sinopec headquarters," said the source who declined to be named because he was not authorised to talk to the media.