CEFC may cut half of its 30,000-strong workforce, the report said, citing Zhuang Jianzhong, vice-director of the company's international research unit.

"We are trying to streamline our business and staff, and hope we can make it through this difficult time," Zhuang said on the sidelines of an energy conference in Shanghai, according to Bloomberg.

His comment comes after CEFC's founder and chairman Ye Jianming was revealed last month to be under investigation for suspected economic crimes.

Chinese authorities have barred senior staff at the conglomerate from travelling overseas.

CEFC's deal to buy a 14.16 percent stake in Rosneft has been uncertain after Ye's investigation raised concerns about the company's high short-term debt load and the lack of transparency over its ownership, while the Chinese government aims to restructure the company.

State-controlled China Huarong Asset Management Co has taken a 36.2 percent stake in CEFC Hainan International, the unit that is acquiring the Rosneft stake.

State-run CITIC Group is conducting due diligence in the possibility it may purchase CEFC's stake in onshore oil fields in Abu Dhabi.

(Reporting by Josephine Mason; Editing by Tom Hogue and Christian Schmollinger)