The new president of Chinese solar giant Wuxi Suntech Power is "assisting an inquiry" at Customs' request, its parent said Tuesday after reports he had gone missing.

Tang Jun was only person from the company helping the investigation and the issue being probed remained unknown, a spokesman for Suntech's parent Shunfeng International Clean Energy (SFCE) told AFP on Tuesday, adding the firm's operations were "all normal".

Tang is the latest senior Chinese businessman to drop out of circulation for unclear reasons.

In January one of China's most prominent clothing firms, Metersbonwe, announced its chairman Zhou Chengjian had returned to work, a week after saying he had disappeared amid speculation he had been caught up in an insider trading investigation.

Weeks earlier Guo Guangchang -- chairman of Fosun, one of the country's biggest private-sector conglomerates -- had vanished from public view in connection with an investigation by authorities, before re-emerging.

Suntech Power was once the world's largest solar panel producer, at a time when Chinese manufacturers were flooding the global market with cheap products, causing trade disputes with the EU and US.

The firm collapsed in 2013 after it announced its main Chinese unit Wuxi Suntech would seek bankruptcy and restructuring, resulting in a bond default in the US worth over half a billion dollars.

The company later said it would receive a $150 million local government bailout and it was eventually bought by Hong Kong-listed Shunfeng for 3.0 billion yuan (now $462 million).

China Business News reported Tuesday that Tang had only taken up his position as president a few months ago and the inquiry could be linked to issues at his previous firm.

SFCE shares were down 1.32 percent in Hong Kong by the break.