BEIJING | Thu Aug 11, 2011 4:18am EDT

BEIJING Aug 11 (Reuters) - Chinese oil majors PetroChina Co Ltd and China Petroleum & Chemical Corp (Sinopec) plan to export between 830,000 and 880,000 tonnes of gasoline in the third quarter, down from about 960,000 tonnes in the second quarter, industry consultancy C1 Energy said on Thursday.

Sinopec would cut gasoline exports to about 30,000 tonnes in the July-September period, only a quarter of its exports in April-June, because of a gasoline supply crunch, C1 Energy said in a report on its website.

Sinopec last week ordered all its plants to run gasoline production units at full rates and maximise gasoline yields as summer peak consumption kicked in and supplies tightened.

Even with production at capacity, Sinopec may still see a gasoline shortage of 300,000 to 400,000 tonnes per month and may want to buy gasoline from rival PetroChina, C1 Energy said.

PetroChina's gasoline export quota, including those from WEPEC refinery, is 800,000 to 850,000 tonnes in the third quarter, slightly higher than the second quarter, but it may divert some cargoes originally planned for export to Sinopec to ensure domestic supply, it added.

China's gasoline output rose 5.1 percent year on year to 46.1 million tonnes in the first seven months of this year, official data showed. (Reporting by Judy Hua and Chen Aizhu; Editing by Chris Lewis and Ken Wills)