China National Petroleum Corp., China's largest energy producer, plans to sell 20 billion yuan ($3.15 billion) worth of six-year medium-term notes on the interbank market in August, a person familiar with the situation said Wednesday.

CNPC will use the proceeds to supplement the company's working capital, said the person, who declined to be named.

Industrial & Commercial Bank of China Ltd. is the lead underwriter of the offering, the person said.