BEIJING (Reuters) - State-controlled China Huarong Asset Management Co has bought a 36.2 percent stake in the unit of CEFC China Energy through which CEFC is acquiring a $9.1 billion (6.57 billion pounds) stake in Russia's Rosneft (>> NK Rosneft' PAO), a filing by the CEFC unit showed.

Huarong (>> China Huarong Asset Management Co Ltd) acquired the stake in CEFC Hainan International in two tranches, in December and in February, according to a filing on Feb. 13 by CEFC Hainan at an online portal run by the State Administration for Industry & Commerce (SAIC).

CEFC subsidiary CEFC Shanghai International Group Co owns the remaining 63.8 percent in CEFC Hainan.

Huarong made the stake purchase through its unit, Huarong Ruitong Equity Investment Management Co.

It was not immediately clear how much Huarong paid for the stake, but the filing showed CEFC Hainan's registered capital expanded by 9.6 billion yuan as a result of Huarong Ruitong's fund injection.

Huarong Ruitong and CEFC did not immediately comment.

Chinese financial publication Caixin, in a story published late Friday, quoted an unnamed China Huarong official as saying the firm did not purchase the stake and instead was ordered to conduct a debt-for-equity swap by the government.

China Huarong could not immediately be reached for comment.

Reuters and other Chinese and international media reported last week that Ye Jianming, the chairman and founder of privately owned CEFC, had been investigated for suspected economic crimes.

CEFC subsequently denied this and said operations were normal.

In just a few years, CEFC has transformed from a niche fuel trader into a rapidly growing oil and finance conglomerate, with assets across the world and an ambition to become one of China's energy giants. It agreed in September to buy a 14.16 percent stake in Rosneft for $9.1 billion.

Huarong Ruitong, responsible for fundraising, project selection, debt acquisition and equity management for Huarong's debt-for-equity swap deals, planned to raise a 50 billion yuan investment fund for deals, Huarong said in early 2017.

(Reporting by Aizhu Chen and Lin Qi; Additional reporting by Shu Zhang and Se Young Lee; Writing by Josephine Mason; Editing by Muralikumar Anantharaman and Stephen Coates)

Stocks treated in this article : NK Rosneft' PAO, China Huarong Asset Management Co Ltd