PetroChina Co and its State-owned parent are planning to sell assets before the end of the year that may include stakes in pipelines and refineries as the country's biggest oil and gas producers seek to shore up their balance sheets, according to sources with knowledge of the situation.

PetroChina and China National Petroleum Corp may announce the stake sales as early as this week, said the sources, who declined to provide details and asked not to be identified. CNPC is seeking to use proceeds from the sale to meet annual income growth targets set by the country's State asset regulators, according to the people.

"Many investors would prefer they cash in on some assets rather than running the assets themselves," Laban Yu, head of Asia oil and gas equities at Jefferies Group LLC in Hong Kong, said by phone.