Li Hejun, Chairman and CEO of Hanergy Holding Group Limited, speaks at a press conference during the Boao Forum for Asia Annual Conference 2013 in Qionghai city, South China's Hainan province, April 7, 2013. [Photo/IC]

Chairman of China's Hanergy Thin Film Power Group dismissed as "rumors" reports that the solar power company is under investigation by Hong Kong's market watchdog.

Li Hejun, the country's former richest man, made the comment during an interview with Xinhua News Agency, after trading in the Chinese solar company's shares was halted last week as the stock price fell nearly 50 percent.

"This is purely a rumor, it's absolutely baseless," Li told Xinhua in the interview posted on Youku.com. He said that if the company was being investigated he would be the first to know. "I should know and I don't know."

He said that Hanergy Thin Power does not owe banks any principal or interest payments and that all of Hanergy's production lines were in full production, with plans to roll out further capacity at a plant in Heyuan in August.

The solar tycoon saw HK$116 billion ($15 billion) of his fortunes wiped out on May 20 as shares in the Hong Kong-listed company plunged 47 percent within 24 minutes and were later suspended. Hanergy said after the meltdown that it was preparing an announcement "containing inside information."

What triggered the plunge is yet not clear. Hanergy's parent company Beijing-based Hanergy Holding Group Ltd said on May 21 that all was well and operations were running as normal.

The statement, which was posted on its website, didn't address Hanergy Thin Film's share plunge nor respond to a report by Reuters that the company was under investigation, but said the group didn't reduce stake in Hanergy Thin Film, nor use its stocks for any derivative trading.

Reuters reported on May 20 that Hanergy Thin Film was under investigation for market manipulation by Hong Kong's Securities and Futures Commission.

Hanergy Thin Film's stock had surged more than sixfold in the past year, making it the world's most valuable solar company worth more than HK$300 billion.

Even with Hanergy's decline, the company is still valued at HK$163 billion, more than four times bigger than US-based First Solar Inc.

According to media reports, Tempe, First Solar and Japan's Solar Frontier K.K. dominate the market for thin-film solar cells.

Agencies contributed to the story.