Sinopec Corp, Asia's largest oil refiner, plans to restructure its retail and wholesale business and sell up to 30 percent of the unit as China's government promotes private investment in the country's oil industry. The state-run company's board passed a resolution on February 19 to restructure the oil product marketing activities and "diversify the ownership by way of introducing social and private capital," it said in a filing with the Hong Kong stock exchange.

The board has authorised the company to bring in "social and private investors" who would acquire up to 30 percent of the business, said Sinopec, formally known as China Petroleum & Chemical Corp .

The statement gave no further details. It did not say whether the sale was open to foreigners, but analysts expect it to be reserved largely for domestic investors.

Sinopec's marketing division contains both wholesale and retail operations, with more than 30,000 petrol stations across the country. The business posted an unaudited operating profit of 27.03 billion yuan ($4.46 billion) for the first nine months of 2013, down 10.5 percent year on year.

Sinopec and other state oil giants such as PetroChina and CNOOC Ltd dominate the oil and gas sector of the world's largest energy user. Private investors have long complained of a lack of access to the lucrative industry.

China's government has vowed to let the private sector play a bigger role in the economy and said in November it was studying ways to allow more private investment in energy as part of broader efforts to boost the economy.

PetroChina, the country's dominant oil and gas producer, has divested part of its pipeline activities, raising billions of dollars.

Neil Beveridge, senior energy analyst at Bernstein Research, expects operating profit at Sinopec's marketing division to rise to 52 billion yuan in 2015 from 42 billion yuan in 2013.

"The divestment of a part of the marketing segment should enable Sinopec to begin to unlock the enormous hidden value within the company," Beveridge wrote in a note to clients.