Chinese state-controlled Huarong Asset Management has bought a 36.2 percent stake in the unit of CEFC China Energy through which CEFC is acquiring a $9.1 billion stake in Russian oil giant Rosneft.

According to CEFC filings seen by Reuters, Huarong has bought the stake in CEFC in two tranches, one in December and one in February. Huarong is controlled by China's Ministry of Finance.

In September, CEFC Energy announced plans to acquire 14.16 percent of Rosneft shares from Glencore and the Qatar Investment Authority (QIA).

As part of a long-term agreement, Rosneft and CEFC Energy inked a deal on crude oil deliveries in 2017. According to the agreement, the Russian oil major will supply CEFC with 60.8 million tons of oil annually until 2023.

"The final structure of Rosneft's shareholders has been formed,"Rosneft CEO Igor Sechin told Rossiya 24 television.