Shares of the solar energy firm rose nearly 5% in morning trade after it said HHLR Management Pte. Ltd was being investigated by the China Securities Regulatory Commission (CSRC) for violating share transfer rules.

Singapore-based HHLR Management is part of Chinese investment giant Hillhouse's public investment arm HHLR.

The CSRC recently published rules that raised the bar for major shareholders to transfer or reduce shares, as part of efforts to ease selling pressure in a wobbly stock market.

HHLR Management was notified by the CSRC of the investigation on suspected rule violations on Wednesday, LONGi said, without giving details.

Hillhouse, controlled by billionaire Zhang Lei, didn't immediately reply to Reuters' request for comment.

The CSRC has tightened scrutiny over share reductions, and has probed alleged rule violations by Eastern Pionner Driving School Co and Nanjing OLO Home Furnishing Co in recent months.

HHLR Management held a 4.98% stake in LONGi at the end of September, compared with 5.85% at the end of 2022, according to filings.

Separately, the Shanghai and Shenzhen stock exchanges published detailed rules on Wednesday that would tighten control of refinancing by listed companies, adding to a growing list of measures aimed at reviving confidence in the stock market.

(Reporting by Samuel Shen in Shanghai and Summer Zhen in Hong Kong; Editing by Varun H K)