(Adds detail of facility leak, background)
SHANGHAI, Aug 4 (Reuters) - Firemen are fighting a blaze at PetroChina's subsidiary refinery and petrochemical plant in northwest China, company officials said on Monday.
The fire that broke out at 8.39 a.m. local time (0039 GMT) was triggered by a leak at an 300,000 tonne-per-year air separation unit, official Xinhua News Agency reported.
A Beijing-based PetroChina media official said so far no casualties have been reported.
It was not immediately clear if other main production facilities were affected by the fire.
The Lanzhou plant, in northwestern Gansu province, is one of the country's oil refining hubs. It operates crude refining capacity of just over 200,000 barrels per day and also an affiliated petrochemical complex.
On Saturday, China suffered its worst industrial accident in a year when an explosion killed at least 69 people and injured more than 120 at a factory that makes wheels for U.S. carmakers, including General Motors. (Reporting by Fayen Wong and Chen Aizhu; Editing by Michael Perry)