Itochu Corp. and Thailand's Charoen Pokphand Group are in talks to invest jointly in CITIC Ltd., the main listed unit of China's first state-owned investment corporation, people familiar with the matter said.

The companies are still waiting for regulatory approval from Chinese authorities, one of the people said, asking not to be identified because the discussions are private. The deal will be strategic in nature, the person said, declining to give a size. CITIC said today it is in preliminary talks with investors, without naming them.

CITIC sold shares to 27 investors including CP Group earlier in the year when it bought $37 billion of assets from its parent. Some investors who did not participate then "remain interested in cooperation with the company," CITIC said in a statement to the Hong Kong stock exchange on Friday.

The Wall Street Journal reported Thursday that CP and Itochu would invest billions of dollars in CITIC, citing unidentified sources. The transformation of Hong Kong-listed CITIC comes as Chinese President Xi Jinping advocates the most sweeping changes since Deng Xiaoping's liberalization in 1978, including allowing more private investment in state businesses. Spokesmen for Itochu, CP Group and CITIC declined to comment.

The asset injection gave the listed company stakes in CITIC Securities Co. and China CITIC Bank Corp., adding financial services to its existing businesses in real estate and mining.