PetroChina Co. Ltd. (PTR) has opened an energy-trading subsidiary in Calgary, according to a person with knowledge of the situation.

The company will buy and sell crude oil, refined products and natural gas, said the person, who asked not to be identified because he isn't authorized to speak for the unit.

PetroChina operates similar offices in Texas and New Jersey, according to the person. PetroChina is a publicly traded unit of state-owned China National Petroleum Corp., the country's largest oil producer.