BEIJING — A Chinese oil tycoon who is buying a stake in Russia's biggest oil producer has been detained for questioning, news reports said Thursday, amid a sprawling anti-corruption crackdown.

The business news magazine Caixin, citing unidentified sources, reported that Ye Jianming, chairman of CEFC China Energy, was under investigation but gave no details. The Hong Kong newspaper South China Morning Post said he was detained Feb. 16 on the orders of Chinese President Xi Jinping.

Phone calls to CEFC's general and publicity offices in Shanghai weren't answered. The company didn't respond to questions sent to the email address of its publicity department.

Ye, 40, adds to a growing number of Chinese businesspeople who have been detained or questioned during a marathon anti-graft crackdown led by Xi.

Ye founded CEFC in 2002 while still in his 20s and was considered one of China's most successful young entrepreneurs. CEFC describes itself as China's biggest privately owned oil company and reported 2016 revenue of $43.7 billion.

Since 2015, Ye's company has been buying energy-related businesses in the Middle East, Africa and Europe.

Last summer, it agreed to pay $9 billion for 14.16 percent of state-owned Rosneft, Russia's biggest oil producer. Glencore, one of the companies that is selling the stake, said the transaction was due to close in the first half of this year.

A former Hong Kong official, Patrick Ho, who headed a think tank supported by Ye's company was arrested in November in New York City on charges he helped arrange bribes for the president of Chad and the Ugandan foreign minister.

U.S. prosecutors said Ho was acting for a Chinese energy conglomerate to secure business advantages but didn't identify the company. CEFC denied it was connected to the case.