A city environmental watchdog has lashed out against a giant petrochemical company and ordered it to apologize to the public in a rare case of government lambasting a State-owned corporation.

The environmental bureau in Lanzhou, capital of Gansu province, listed four major pollution incidents by PetroChina's Lanzhou Petrochemical Co since last August and demanded an apology.

The main incident involved a leak of ethylene that caused a fire on Aug 4 last year. Other incidents involved air pollution and the improper disposal of dangerous waste.